G482 Revision Ques3ons Part 1
Ques3on 1 Explain what an electric current is
Answer 1 Rate of flow of charge
Ques3on 2 Define what a conven3onal current is
Answer 2 Describes the movement of charge of posi3ve par3cles from + to -
Ques3on 3 Describe what is meant by electron flow
Answer 3 The movement of electrons from to +
Ques3on 4 Define the Coulomb
Answer 4 Unit of charge = 1As
Ques3on 5 What is the difference between an electric current and an electrolyte?
Answer 5 Electric current is electrons moving. Electrolyte current is ions moving
Ques3on 6 How do you use an ammeter to measure the current of a circuit?
Answer 6 Place an ammeter in series anywhere in the circuit
Ques3on 7 What is the charge of an electron?
Answer 7 - e=- 1.6x10-19 C
Ques3on 8 Define Kirchoff s first law. What is this a conserva3on of?
Answer 8 The sum of the currents entering a junc3on is equal to the sum of the currents exi3ng the junc3on. Conserva3on of charge
Ques3on 9 State what is meant by mean dri] velocity of charge carriers
Answer 9 Average velocity of an electron as it travels through a wire due to a PD
Ques3on 10 What is the difference between conductors, insulators and semiconductors?
Answer 10 Conductors have a greater number density of electrons
Ques3on 11 Define Poten3al difference
Answer 11 The amount of energy per charge converted from electrical into another form
Ques3on 12 Define EMF
Answer 12 The amount of energy per charge converted from one form into electrical
Ques3on 13 Define the volt
Answer 13 JC - 1
Ques3on 14 Describe how you can use a voltmeter to measure the PD of a component
Answer 14 Place is around the component (parallel to it)
Ques3on 15 Define the Ohm
Answer 15 1VA - 1
Ques3on 16 State Ohm s law
Answer 16 Electric current through a conductor is propor3onal to the PD across it provided physical condi3ons are kept constant (temp)
Ques3on 17 Define resistance
Answer 17 A property that regulates the amount of current flowing through it R=V/i
Ques3on 18 What does the I- V graph look like for an Ohmic device
Answer 18
Ques3on 19 What does the I- V graph look like for a filament lamp
Answer 19
Ques3on 20 What does the I- V graph look like for an LED
Answer 20
Ques3on 21 Describe an experiment to determine the I- V graph of a component
Answer 21 Ammeter in circuit, voltmeter around component. Measure PD and current. Change resistance in circuit and repeat. Make graph of results
Ques3on 22 Describe an advantage of using LED s
Answer 22 Robust, low PD, long life, switch on instantly
Ques3on 23 Define the resis3vity of a material
Answer 23
Ques3on 24 What is the equa3on for resis3vity
Answer 24
Ques3on 25 Describe how the resis3vity's of metals and semiconductors are affected by temperature
Answer 25 Increase temperature it increases resis3vity
Ques3on 26 Describe what is meant by the displacement of a wave
Answer 26 The distance a point of the wave has from the rest point
Ques3on 27 How is the resistance of a wire affect by temperature
Answer 27 As you increase the temperature, the resistance decreases
Ques3on 28 How is the resistance of a NTC thermistor affected by temperature
Answer 28 As you increase the temperature, the resistance decreases
Ques3on 29 Describe what power is
Answer 29 Rate that electricity is transferred/ work is done
Ques3on 30 Explain how a fuse works
Answer 30 A piece of wire that melts and breaks a circuit when a high current causes it to heat up
Ques3on 31 How do you determine the correct fuse to use?
Answer 31 Choosing a current ra3ng that is slightly above the current that the wire will be carrying
Ques3on 32 Define what a kilowal- hour is
Answer 32 Energy used by a 1kW appliance in 1hour=3.6MJ
Ques3on 33 Describe the equa3on to calculate energy in kilowal- hours
Answer 33 Energy=Power x 3me Power is measured in kw 3me is measured in hours
Ques3on 34 Describe what Kirchoff s second law is. What is it a conserva3on of?
Answer 34 The sum of the EMF is equal to the sum of the PD s in a closed loop
Ques3on 35 How do you calculate the total resistance of resistors in series?
Answer 35 Add the resistances together
Ques3on 36 How do you calculate the total resistance of resistors in parallel?
Answer 36
Ques3on 37 What is meant by internal resistance?
Answer 37 There resistance provided by a source of EMF (balery or cell)
Ques3on 38 What is meant by the term terminal PD?
Answer 38 The PD across the terminals of a balery
Ques3on 39 What is the equa3on for EMF including internal resistance?
Answer 39 EMF=i(R+r)
Ques3on 40 What does a poten3al divider do?
Answer 40 A circuit containing 2 components designed to divide the PD up into propor3on to their resistor
Ques3on 41 How does the resistance of an LDR change as the light intensity increases?
Answer 41 As intensity increases resistance decreases
Ques3on 42 Describe an advantage of using data loggers
Answer 42 Measurements taken at correct 3me, does not need person there, automa3c readings, less human error
Ques3on 43 Describe what a longitudinal wave is
Answer 43 Waves where the oscilla3ons are parallel to the direc3on of travel
Ques3on 44 Describe what a transverse wave is
Answer 44 Waves where the oscilla3ons are perpendicular to the direc3on of travel
Ques3on 45 Describe what the amplitude and displacement of a wave is
Answer 45 Amplitude = maximum displacement of a point from its rest posi3on
Ques3on 46 Describe what frequency and period are for a wave
Answer 46 The number of oscilla3ons per unit 3me. The 3me taken for one complete palern of oscilla3on
Ques3on 47 What is the wave speed equa3on?
Answer 47
Ques3on 48 Explain what is meant by refrac3on for light
Answer 48 Where light changes direc3on when moving from one medium into another due to a difference in density and wave speed
Ques3on 49 Explain what is meant by reflec3on for light and sound
Answer 49 Where the wave reflects from a surface
Ques3on 50 Explain what is meant by diffrac3on of light and sound
Answer 50 Where a wave spreads out when passing around an object or through a gap