GCSE Separate Science Physics
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| 1 Describe an atom | A positively charged nucleus orbited by negative electrons on shells
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| 2 What type of charge is on a proton | Positive
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| 3 What type of charge is on an electron | Negative
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| 4 What the overall charge of the nucleus | Positive
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| 5 What is the overall charge of an atom | Zero
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| 6 What is the role of the voltage in a circuit | To Push the electrons around the circuit
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| 7 What provides the voltage | The power supply (battery, cell or power pack)
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| 8 What is the direction of electron flow | Negative terminal to Positive terminal
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| 9 What is the direction of conventional current flow. | Positive terminal to negative terminal
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| 10 What is a series circuit | A circuit in which the current only has one path to flow through.
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| 11 what is a parallel circuit | A circuit in which the current has more than one path to flow through
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| 1. Define electric current. | The rate of flow of charge
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| 2. What instrument is used to measure current? | Ammeter
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| 3. What is the unit of current? | Ampere or Amps
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| 4. How is current measured in a circuit or a component of a circuit? | Ammeter connected in series with the component
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| 5. What is another name for Voltage? | Potential difference
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| 6. Why is a potential difference needed in a circuit? | To push the electrons around the circuit
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| 7. What is the unit of Voltage? | Volts
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| 8. What instrument is used to measure Voltage? | Voltmeter
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| 9. How is the voltage of components measured in a circuit? | In parallel across the component
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| 10. How can the conservation of charge is a series circuit be summarised? | The rate of flow of charge is current and the current is the same at all points in a series circuit.
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| 11. How can the voltage across components in a series circuit be summarised? | The voltage from the source is shared across the resistors proportionally.
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| 12.How can the conservation of charge is a parallel circuit be summarised? | The rate of flow of charge is current and the sum of the currents going into a junction is equal to the sum of the currents leaving the junction
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| 13. If the current through A1 is 2.5A, what is the current in A2 and A3? | Ammeter 2 = 2.5A ,Ammeter 3 = 2.5A
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| 14. If the current from the cell is 1.5A and all 3 lamps are identical, what is the current through each lamp? | Current through each lamp is 0.5 A
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| 15. The voltage across the source is 15V and all the resistors have identical resistances, what is the voltage across each resistor? | Voltage across each resistor is 5V
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| 16. The voltage across the source is 4.5V and all three lamps have identical resistances, what is the voltage across each resistor? |
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| 1. What is the unit of electric charge? | Coulomb
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| 2.What is the definition of the coulomb | 1 Coulomb is the charge that pass a point in a circuit when there is a current of 1 amp for 1 second
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| 3.What are these charges called in metals | electrons
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| 4. What is the charge on an electron | 1.6x 10-19Coulomb
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| 5. What is electric current? | The rate of flow of charge
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| 6. State the equation with units of each variable linking charge, current and time? | Charge (Q) in Coulomb (C) = Current (I) in amps (A) x time (t) in Seconds (S)
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| 7 Make each variable of the equation in number 6 the subject of the formula. | Q=Ixt I = Q/t and t = Q/I
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| 8. The current through a lamp is 2A, how much charge would flow in 5 minutes? | 5 minutes = 5x60 =300 seconds ,Q = I x t, Q = 2A x 300s , Q = 600C
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| 9. A heater uses 5A of current and has 1200C flowing. For how long was the heater on? | Q = I x t, t = Q/I t = 1200C/5A t = 240 sec
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| 10. A charge of 36,000C flows for half an hour through a lamp, what current flowed through the lamp? | Q = I x t, I = Q/t, t = 30min = 30 x 60 = 1800 sec
I =Q/t, I = 36,000C/1,800sec I = 20A
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| 11. State the equation with units of each variable linking charge, energy and Volt? | Energy (E) in joule(J) = Charge (Q) in Coulomb (C) x Voltage (V) in Volts (V)
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| 12. The volt is a derived unit, how can the volt be expressed in base units? | 1V = 1J/s
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| 13. 900 J of energy was supplied to a lamp as 270C of charge flowed through it, what is the voltage across the lamp? | E = Q x V, V = E/Q, V = 900J/270C, V = 3.33V
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| 14. Calculate the energy used up when 25C passes through a wire with a voltage of 1.2V across it. | E = Q x V, E = 25C x 1.2V, E = 30J
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| 15. How much charge flows through a lamp with 1.5V across it while 45J supplied to it. | E = Q x V, Q = E/V, Q = 45J/ 1.5V, Q = 30C
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| 10. How does the resistance of a light dependent resistor changes with light intensity. | Resistance decreases with light intensity
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| 11. How does the resistance of a thermistor changes with temperature? | Resistance increases with a fall in temperature
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| 12. How can we find the resistance from any of the 3 graphs in number 9. | Find the reciprocal of the slope of the graph or points on the graph.
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| 13.Describe the resistance of the Ohmic resistor | The resistance remains the same
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| 14.Describe the resistance of the Diode | High resistance in one direction and a low resistance in the other direction. So current can only flow in one direction.
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| 15.Describe the resistance of the filament lamp |
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| 1 Fill in the gaps When a -------------- passes through a resistor, energy is --------------------- because electrical ---------- is done against the ----------------------, during which the resistor becomes ---------------. | current, transferred, work, resistance , warm
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| 2 State two instances where the heating effect is useful and two instance where it is not useful | Useful: Electric heater and electric kettle ,Not useful: computers and plugs
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| 3 What does the word dissipates mean? | Spread out
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| 4 What happens to the surroundings when heat dissipates? | The surroundings warms up
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| 5 use the diagram to assist you to explain the heating effect of an electric current. | As the electrons flow down the wire, they collide with the ions and transfer energy so the ions vibrate more vigorously. So it becomes more difficult for the electrons to flow so the resistance to increases. The excess heat is dissipated to the environme
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| 6 State three ways to reduce resistance. | 1 Use wires with low resistance eg Copper
2 Use thick wires as they have lower resistance
3 Cool the metal to reduce the vibrations in the lattice.
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| 7 State the worded equation for electrical energy transferred | Electrical energy = Current x Voltage x time
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| 8 State the equation for electrical energy transferred in symbols | E = I x V x t
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| 9 Calculate the energy transferred when a toaster using 230V mains using a current of 3A for 2 minutes. | E = I x V x t E = 3A x 230V x120s, E = 82,800J
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| 10 Calculate the current needed to operate a TV set using 207kJ of energy for half an hour | E = I x V x t I = E/ V x t I = 207,000J/230V x30x60s I = 0.5A
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| 1Define power | The rate at which energy is transfered
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| 2State the unit of power and its symbol | Unit of power is Watt symbol is W
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| 3 state the worded and symbol equation relating power, energy and time | Power= energy divide by time, P =E/t
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| 4 state the worded and symbol equation relating power, current and voltage | Power = current multiplied by voltage P = I x V
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| 5 state the worded and symbol equation relating power, current and resistance | Power = Current squared multiplied by resistance, P = I2x R
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| 6. 9kJ of energy is transferred in 2 minutes, what is the power transferred? | P =E/t 2 minutes = 120s, 9kJ = 9,000J, P = 9000J/ 120s P = 75W
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| 7 When a current of 3.5A flow through a lamp with potential difference of 60V, what is the power transferred through the lamp? | P = I x V, P = 3.5A x 60V, P = 210W
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| 8 What is the power transferred when 6A of current flows through a radio with a resistance of 5Ω | P = I2x R, P = 62 x 5, P =36 x 5, P = 180W
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| 9 Fill in the blank:The power through a circuit or an appliance is directly ------------to the ------------and the ------------- | Proportional current, and voltage
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| 10 state 3 ways of working out the power of an electric device | 1 Divide the energy transferred by the time it took 2 multiply the current through the device by the voltage across the device.3 Multiply the current squared through the device by the resistance of the device
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| A 3-pin plug connect an appliance safely to the mains supply. Give the role of each of the following. 1 The live wire | The live wire connects the appliance to the generator at the power station.
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| 2 The Earth wire | Connects the metal parts of the appliance to a large metal spike that is pushed in the ground
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| 3 The neutral wire | Provides a return path to the power station
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| 4 What is the voltage on the earth wire? | 0V
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| 5 What is the voltage on the Live wire? | 230V
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| 6 What is the voltage on the neutral wire? | 0V
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| 7 Fuses are marked with the current it can carry, what are the usual current values | 3A, 5A or 13A
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| 8. Which wire normally have a brown or red colour | Live wire
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| 9. Which wire normally have green and yellow colours | Earth wire
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| 10. Which wire normally have a blue colour? | Neutral wire
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| 12. How is a fuse adapted for safety | A current passes through the wire the wire gets hot and if the current exceeds a curtain value the fuse wire melts and the circuit is broken which prevents current from flowing.
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| 13. What are the dangers involved when a faulty appliance does not have an earth wire connected to the metal parts of the appliance. | If you touch the metal parts, you will have a dangerous shock as the current flows through you to the ground that is 0V and the live wire is 230V. Causing a potential difference of 230V through your body.
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| 14 How does circuit breakers operate | They detect a change in current and safely switch off the power supply.
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| 15 Two advantages of circuit breakers over fuse. | 1. A circuit breaker chips out immediately as it detects the change in current where as a fuse needs to heat up and burn because of a change in current.2. Once the situation is rectified the circuit breaker can be reset but a fuse has to be replaced.
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| State the rule for current in a series circuit | the current is the same at every point in the circuit and in every component
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| State the rule for potential difference in a series circuit | the total potential difference of the power supply is shared between components
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| State the rule for resistance in a series circuit | the more resistors, the greater the resistance. RT=R1+R2
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| State the rule for current in a parallel circuit | the total current through the whole circuit is the sum of the currents through the separate components
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| State the rule for potential difference in a parallel circuit the potential difference across each branch in the circuit is the same |
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| State the rule for resistance in a parallel circuit | adding more resistors in parallel decreases resistance
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| What colour is the live wire in a three core cable? | brown
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| What colour is the neutral wire in a three core cable? | blue
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| What colour is the earth wire in a three core cable? | green and yellow
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| The brown wire in a plug is the _______ | live
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| The blue wire in a plug is the ________ | neutral
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| The green and yellow wire in a plug is the ________ | earth
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| The potential difference between the live wire and others in the plug is _____ V | 230V
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| Current flows into an appliance through the _______ wire | live
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| Current flows out of an appliance through the ______ wire | neutral
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| The _________ wire is a safety feature of appliances | earth
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| Potential difference between the neutral wires and others in the plug should be ____ V | 0V
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| Electric Current is….? | the flow of electric charge
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| Potential difference between two points in a circuit is….? | the work done when a couloumb of charge passes between the points.
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| In a circuit the potential difference causes …..? | charge to flow
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| Resistance is…? | caused by anything which opposes the flow of electric charge
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| Particles which can be 'charges' in electric circuits are… | electrons or ions
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| What is a series circuit? | A circuit with only one route for charge to flow
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| What is a parallel circuit? | A circuit with more than one route for charge to flow
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| State the equation which links charge flow, current and time | Q=It
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| State the equation which links current, potential difference and resistance | V=IR
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| State the equation which links current, potential difference and power | P=IV
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| State the equation which links current, power and resistance | P=I2R
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| State the equation which links energy transferred, power and time | E=Pt
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| State the equation which links charge flow, energy transferred and potential difference | E=QV
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| What is the unit of charge flow? | Coulomb ( C )
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| What is the unit of current? | Amps (A)
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| What is the unit for potential difference? | Volts (V)
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| What is the unit for resistance? | Ohms (Ω)
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| What is the unit for power? | Watts (W)
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| Draw the I-V characteristic for a fixed resistor | teacher to draw on board…
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| Draw the I-V characteristic for a filament lamp see | teacher to draw on board…
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| Draw the I-V characteristic for a diode | teacher to draw on board…
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| Describe the I-V characteristic for a fixed resistor | Current and potential difference are directly proportional, resistance is constant
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| Describe the I-V characteristic of a filament lamp | Resistance is not constant, it increases as p.d. increases
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| Explain why resistance increases with increased p.d. in a filament lamp | temperature increases causing ions to vibrate and increasing collisions with electrons flowing through the filament
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| Describe the I-V characteristic of a diode | The current only flows through the diode in one direction, there is a very high resistance in the reverse direction.
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