Electricity

Question 1

1. What do we use circuit symbols to show?
2. What is the difference between series and parallel circuits?

Answer 1

1. To show the different components of a circuit
2. Series use one single loop, whereas Parallel use more than one loop.

Question 2

1. What are charged particles known as?
2. What is the units of charge?

Answer 2

1. A charged particle is an electron
2. The units on charge is Coulombs (C)

Question 3

1. What is current?
2. What is the units of current?

Answer 3

1. Current is the rate of flow of charge (how much charge flows every second)
2. Current has the unit amps (A) and is measured by an ammeter (which goes in series)

Question 4

What equation links charge, current and time?

Answer 4

Q = I X t

I = Q / t
t = Q / I

I = Current (Amps, A)
Q = Charge (Coulombs, C)
t = Time (s)

Question 5

What are the circuit symbols?

Answer 5

Look up, (photo in camera roll, downloads/ online)

Question 6

What is potential difference?

Answer 6

Potential difference (also known as voltage) is a measure of how much energy is transferred to (or by) each coulomb of charge.

Question 7

What is the units of potential difference and how is it measured?

Answer 7

Potential difference has the units of volts and is measured by a voltmeter (which goes in parallel)

Question 8

What equation is used to find energy transferred?

Answer 8

E = V X Q

V = E / Q
Q = E / V

E = Energy (Joules, J)
Q = Charge (Coulombs, C)
V = Voltage (Volts, V)

Question 9

1. What is resistance?
2. What does a higher resistance mean?

Answer 9

1. Resistance is a measure of how hard it is for the current to pass through a component in a circuit.
2. A higher resistance means it is harder for the current to pass through the component. (Higher = Harder)

Question 10

What does Ohm’s law state?

Answer 10

That the current in a resistor is proportional to the potential difference. (Provided the temperature is at a constant)

Question 11

What is the equation to find resistance?

Answer 11

R = V / I

V = I X R
I = V / R

I = Current (Amps, A)
V = Voltage (Volts, V)
R = Resistance (Ohms, Ω)

Question 12

What is the relationship between volts and current?

Answer 12

As volts decreases, current decreases, and vice-versa

Question 13

What is the power of an appliance?

Answer 13

The energy transferred to an appliance each second

Question 14

What is the formula to find power?

Answer 14

P = E / T

E = P X T
T = P / E

P = Power (Watts, W)
E = Energy (Joules, J)
T = Time (seconds, s)

Question 15

1. In a series circuit the current flows through ___ continuous path. This means that the current must be ___ ___ at all parts in a series circuit.
2. How does this compare to a parallel circuit?

Answer 15

1. In a series circuit the current flow through one continuous path. This means they the current must be the same at all parts in a series circuit.
2. In a parallel circuit, they are multiple paths the current can take, this mean the current splits and the current wont be the same at all parts of a parallel circuit.

Question 16

In a series circuit, what is the relationship between the voltage supplied by the battery and the potential difference across the components?

Answer 16

The sum of the potential difference across the components equals the battery voltage.

Question 17

In a series circuit, what is the relationship between the voltage supplied by the battery and the potential difference across the bulbs?

Answer 17

The sum of the potential difference across the battery is the same as the potential difference (voltage) across each bulb.

Question 18

1. As the temperature increases, what happens to the resistance of a thermistor?
2. As light intensity increases, what happens to the resistance of an LDR?

Answer 18

1. As temperature increases, the resistance of a thermistor decreases.
2. As the light intensity increases, the resistance of an LDR decreases.

Question 19

What are sensing circuits used in?

Answer 19

Sensing circuits are used in central heating that turns on when its cold, lights that turn on when its dark, or automatically opening doors.

Question 20

1. If an appliance has a metal casing, what does it need? Why?
2. If an appliance has plastic casing, does it need this? What is the name for it?

Answer 20

1. An appliance with metal casing needs an earth wire for safety.
2. If an appliance has plastic casing, it doesn’t need an earth wire, it is known as double insulated.

Question 21

1. What is the correct size of fuse for an appliance?
2. What is the largest domestic fuse size? What appliances is it reserved for?

Answer 21

1. The correct size of fuse is one that is slightly above the regular operating current.
2. The largest domestic fuse size is BA, it is reserved for high power devices such as electric radiators.

Question 22

What is a circuit breaker?

Answer 22

A circuit breaker is a resettable switch that trips if too large a current flows.

Question 23

1. ___ ___ (D.C) only flows in ___ direction.
2. ___ ___ (A.C) constantly changes direction.

Answer 23

1. Direct Current (D.C) only flows in one direction
2. Alternating Current (A.C) constantly changes direction

Question 24

What voltage and hertz is Mains electricity, is it AC or DC?

Answer 24

Mains electricity flows at 230 Volts, and 50 Hertz, it is AC.

Question 25

What are the 3 wires, what colour are they and what is their purpose?

Answer 25

1. The live wire (brown) carries the AC
2. The neutral wire (blue) completes the circuit
3. The earth wire (yellow and green) is a safety wire

Question 26

What supplies D.C?

Answer 26

A battery or cell