P2.4 Current Electricity

Question 1

What is a fuse?

Answer 1

A safety measure designed to melt and breaks the circuit

Question 2

What is a voltmeter?

Answer 2

It is used to measure potential difference (voltage).

Question 3

What is an ammeter used for?

Answer 3

It is used to measure electrical current.

Question 4

What does a fixed resistor do?

Answer 4

It limits the current in a circuit.

Question 5

What does a diode do?

Answer 5

It allows the current to flow in one direction.

Question 6

What does a switch do?

Answer 6

It allows the circuit to be closed and opened to allow flow.

Question 7

What does a heater do in a circuit?

Answer 7

It transfers electrical energy into heat energy and emits it.

Question 8

What does a variable resistor do?

Answer 8

It limits the current but can be changed.

Question 9

What does an indicator (bulb) do?

Answer 9

It is a light source and shows the flow of electricity.

Question 10

What does a light emitting diode (LED) do?

Answer 10

It emits light when current passes through it.

Question 11

What is the equation for time, current and charge flow?

Answer 11

Current(amps) = charge flow (coulombs) /time taken(seconds)

Question 12

What is the equation for voltage, current and resistance?

Answer 12

Voltage = current x resistance

Question 13

The ….. is always the same anywhere in a series circuit.

Answer 13

Current

Question 14

….. is shared across all components in a circuit.

Answer 14

Voltage

Question 15

The total ….. of the circuit is the separate resistors added together.

Answer 15

Resistance

Question 16

The total ….. through the whole circuit is the sum of the currents in each ‘loop’ of the circuit.

Answer 16

Current

Question 17

The ….. across each component is the same.

Answer 17

Potential difference (voltage)

Question 18

….. that are different will change the current flowing through it.

Answer 18

Resistors

Question 19

Explain how a Van der Graff works.

Answer 19

The belt in the Van der Graff rubs against a felt pad.
The belt becomes positively charged because electrons are ‘scraped off’.
The belt carries that charge onto the metal dome.
The dome becomes charged.
The charge transfers to you and your hair becomes positively charged.
Your hair separates because the positive charges repeal each other.

Question 20

When a polythene rod is rubbed with a dry cloth, how and where are electrons transferred?

Answer 20

Electrons from the cloth transfer onto the atoms in the rod, which makes the rod become negatively charged and the cloth become positively charged.

Question 21

When a perspex rod is rubbed with a dry cloth, how and where are electrons transferred?

Answer 21

Electrons from the rod are transferred onto atoms in the cloth, which makes the rod become positively charged and the cloth become negatively charged.

Question 22

What is resistance?

Answer 22

The force opposing electron flow in a circuit created by ions in the wires

Question 23

What is potential difference?

Answer 23

The difference in energy between one point and the next

Question 24

Explain why resistance will increase with heat.

Answer 24

Thermal energy will transfer into kinetic energy. Therefore, the ions gain more energy to bump into the electrons.