Download Answer - Hodge Hill College

1)
a)
b)
c)
Current is the rate of flow of…..
Energy
Charge
protons
Answer
b) Charge
Bonus
What is the unit of current?
Answer
Amps, A
2) Voltage (potential difference) is the ……..?
a) Energy transferred per unit charged passed
b) The rate of charge per second
c) Current transferred per unit charged passed
a) Energy transferred per unit charged passed
The driving force that pushes the current around
Bonus
What is the unit for Voltage?
Answer
Volts, V (or a Joule / Coulomb, J/C)
3) 1 volt is equal to…
a) 1 joule/charge
b) 1 joule/coulomb
c)
1 Joule/amp
b) 1 joule/coulomb
4) Resistance is…..;
a) Rate of flow of charge
b) Anything that slows down the flow of
current.
Answer
b) Anything that slows down the flow of current.
Bonus
What is the unit of resistance?
Answer
Ohms, Ω
5) The bigger the voltage supplied to a
circuit…
a) The more the energy
b) The less the energy
Answer
a) The more the energy.
6) At junction in a circuit the current is….
a) Split
b) Stays the same
a) Split
7) 6) At junction in a circuit the voltage is….
a) Split
b) Stays the same
Ans:
b) Stays the same
8). Ammeter in a circuit measures ….
a) Voltage
b) Current
c) Resistance
Ans:
Current
Bonus: An ammeter is placed in….
a) Series
b) In parallel
Bonus: An ammeter is placed in….
a) Series
9) Voltmeter in a circuit measures ….
a) Voltage
b) Current
c) Resistance
.
Ans:.
a) Voltage
Bonus: An Voltmeter is placed in….
a) Series
b) In parallel
Bonus: An ammeter is placed in….
a) Parallel around the component
10) What is a variable resistor used for?
Ans:
• Changes the resistance of the circuit which in turn
changes the current
11) What are the three voltage-current graphs that must
be known (3)
Ans:
a) Fixed resistor
b) Filament bulb
c) Diode
12) Describe using a graph how the current varies with
the voltage in a fixed resistor.
Ans:
Current
Voltag
e
1. Resistor (Constant
temp)
Current increases in
proportion to voltage
13) Describe using a graph how the current varies with
the voltage in a filament bulb?
Ans:
.
Current
Voltag
e
2. Bulb (Filament Lamp)
As voltage increases the bulb
gets hotter and resistance
increases, current levels off
14) Describe using a graph how the current varies with
the voltage in a diode? (2)
Ans:
Current
Voltag
e
3. Diode
A diode only lets current
go in one direction – it
has very high resistance
in the other direction
15) What is the formula that links current and voltage?
(2)
Ans:
V= I X R
Potential difference = Current X Resistance
16) What is a LDR ? (2)
Ans:
• It is a light dependent resistor
• It’s a resistor that changes its resistance according to
the amount of light it receives.
17) Use a graph to describe how the resistance varies
with the light ? (2)
Ans:
In bright light the resistance falls-so curent increases
In darkness , the resistance is the highest
Resistance
1) Light dependant
resistor – resistance
DECREASES when
light intensity
INCREASES
Amount of light
18) Use a graph to describe how the resistance varies
with the temperature in a thermistor? (2)
Ans:
In hot conditions the resistance falls-so current
increases.
In cool conditions , the resistance goes up.
Resistance
2) Thermistor – resistance
DECREASES when
temperature INCREASES
Temperature
19) Why does an electric component (resistor) become
hot when current passes through it ? (2)
Ans:
• There is energy transfer so resistor heats up.
• Energy transfer is because
• electrons collide with ions in the lattice as they move
through it.
• These collisions give ions extra energy which is
emitted as heat.
20) Heating effect ……
a) Increases the resistors resistance so less current will flow.
b) Decrease the resistors resistance so less current will flow.
c) Decrease the resistors resistance so more current will flow.
Ans:
a) Increases the resistors resistance so less current will
flow.
21) Heating effect can cause ……
a) Can make electrical devices more efficient because less energy is
wasted as heat.
b) Can make electrical devices less efficient because more energy is
wasted as heat.
c) Has no effect on the efficiency of the device.
Ans:
b) Can make electrical devices less efficient because more
energy is wasted as heat.
22) Give an example of how the heating effect of an
electric current can be useful.
Ans:
• Electric toaster or heater.
• Toaster or heater contains a coil with very high
resistance.
• When a current flow through the coil, temperature
shoots up, leading to infra-red radiation being given
off.
• Infra-red radiation cooks the bread in the toaster.
23) What is the equation which links electrical power
with current and voltage?.
Ans:
• Electrical power = potential difference x current
Bonus
• What is the definition of electric power?
Answer
• The rate at which energy is transferred in an
appliance?
24) High power appliances …
a) Draw small currents
b) Large currents
Ans:
b) Large currents
Bonus
What is the unit for power?
Answer
Watts (W)
25) What is the equation that links energy transferred,
current, voltage and time
Ans:
Electrical energy = Current X Potential difference X Time
Electrical energy = IxVxt
Bonus
The energy transferred by a component is dependent on
….
Answer
The current through it, the voltage supplied and how long
it is on for measured in seconds.