Copy the table and complete it by adding names and symbols of the devices described. Name of the device Circuit symbol Description Resistance decreases when light falls on it. Resistance changes when temperature changes. An electromagnetic switch.

It will be important for you to learn the circuits containing resistors, switches, ammeter, voltmeter and be familiarised with their symbols. Resistors are used to control the flow of current in a circuit. Relays are switches that works using an electromagnet. Name of the device Circuit symbol Description Light dependent resistor Resistance decreases when light falls on it. Thermistor Resistance changes when temperature changes. Electrical relay An electromagnetic switch.

E M B I B E

Cambridge IGCSE® Physics Coursebook Second Edition>Chapter 19 - Electric Circuits>Questions>Q 19.13

MEDIUM

Upper Secondary: IGCSE

IMPORTANT

Earn 100

Two resistors of values $30 Ω$ and $60 Ω$ are connected in parallel. Calculate their effective resistance.

Important Questions on Electric Circuits

MEDIUM

Upper Secondary: IGCSE

IMPORTANT

Cambridge IGCSE® Physics Coursebook Second Edition>Chapter 19 - Electric Circuits>Questions>Q 19.18

In normal use, a current of

3.5 A

flows through a hairdryer. Choose a suitable fuse from the following:

3 A, 5 A, 13 A, 30 A

. Explain your choice.

MEDIUM

Upper Secondary: IGCSE

IMPORTANT

Cambridge IGCSE® Physics Coursebook Second Edition>Chapter 19 - Electric Circuits>Questions>Q 19.19

Why are fuses fitted in the fuse box of a domestic electricity supply?

MEDIUM

Upper Secondary: IGCSE

IMPORTANT

Cambridge IGCSE® Physics Coursebook Second Edition>Chapter 19 - Electric Circuits>Questions>Q 19.19

What device could be used in place of the fuses?

MEDIUM

Upper Secondary: IGCSE

IMPORTANT

Cambridge IGCSE® Physics Coursebook Second Edition>Chapter 19 - Electric Circuits>Questions>Q 19.2

What hazards can arise when the current flowing in an electrical wire is too high?

HARD

Upper Secondary: IGCSE

IMPORTANT

Cambridge IGCSE® Physics Coursebook Second Edition>Chapter 19 - Electric Circuits>End-of-chapter questions>Q 1

Copy the table and complete it by adding names and symbols of the devices described.

Name of the device	Circuit symbol	Description
		Resistance decreases when light falls on it.
		Resistance changes when temperature changes.
		An electromagnetic switch.