Topic 3 - Basic electricity

Question 1

Units

Answer 1

(E) Energy - joules (J)
(Q) Charge - Coulombs (C)
(V) Voltage - Volts (V)
(I) Current - Amps (A)
(R) Resistance - Ohms (Ω)

Question 2

Equations

Answer 2

1. Energy = voltage x charge (E=VxQ), Voltage = energy ÷ charge (V=E÷Q), Charge = energy ÷ voltage (Q=E÷V)
2. Charge = current x time (Q=IxT), Current = charge ÷ time (I=Q÷T), Time = charge ÷ current (T=Q÷I)
3. Voltage = current x resistance (V=IxR), Current = voltage ÷ resistance (I=V÷R), Resistance = voltage ÷ current (R=V÷I)
4. Resistance = voltage ÷ time (R=V÷T), Voltage = resistance ÷ time (V=R÷T), Time = resistance ÷ voltage

Question 3

Lamp

Question 4

Cell

Question 5

Battery

Question 6

Ammeter

Question 7

Voltmeter

Question 8

Resistor

Question 9

Current- series

Answer 9

The current is the same at all parts in the circuit.  

Question 10

Current- parallel

Answer 10

The total current in the circuit is the sum of the currents through the separate branches. (Current splits at a junction and how the current splits depends on the relative resistance of each branch).

Question 11

Voltage- series

Answer 11

The total voltage is divided (shared) between the components.

Question 12

Voltage- parallel

Answer 12

The voltage is the same across each branch in the circuit, and is equal to the voltage of the power supply

Question 13

Resistance- series

Answer 13

The total resistance is the sum of the separate resistances. As you add more components in series, the total resistance increases and the total current decreases.

Question 14

Resistance- parallel

Answer 14

The total resistance reduces as you add more components in parallel. The total resistance in a parallel circuit is equal to the sum of the inverse of each individual resistances.

Question 15

Current

Answer 15

The rate of flow charge

Question 16

Voltage

Answer 16

The energy transferred per unit charged passed

Question 17

Electric current in solid metallic conductor

Answer 17

In solid metallic conductors is a flow of negatively charged electrons

Question 18

Why is current protected at a junction in a circuit?

Answer 18

This is because current is conserved as no charge has been gained or lost.

Question 19

What do lamps & LEDs help with in a circuit?

Answer 19

Can be used to show the presence of current a circuit

Question 20

Describe the effect of the current in a circuit when the resistance is changing?

Answer 20

As you increase the resistance in a circuit, the current will decrease

Question 21

Increases voltage in the circuit

Answer 21

Decrease the resistance in a circuit, the current will increases voltage