Grade 9 Topics

What happens when a solid is heated and expands?

• The molecules do not change size and the spaces between the molecules become larger.

• The molecules expand and the spaces between the molecules become larger.

• The molecules expand and the spaces between the molecules become smaller.

• The molecules expand and the spaces between the molecules do not change size.

The diagram shows two divergent rays of light from an object O being reflected from a plane mirror.

At which position is the image formed?

• A

• B

• C

• D

Which statement is correct?

• Total internal reflection only occurs when light travels from air into glass.

• The larger the refractive index of glass, the larger is the critical angle.

• When total internal reflection occurs, the angle of incidence is equal to the angle of reflection.

• When total internal reflection occurs, the angle of incidence is less than the critical angle.

A young person with healthy ears can hear a range of frequencies.

What is the approximate range of frequencies?

• 2 Hz to 2000 Hz only

• 2 Hz to 20 000 Hz only

• 20 Hz to 2000 Hz only

• 20 Hz to 20 000 Hz only

An electric current in a wire is into the page.

Which diagram shows the shape and direction of the magnetic field around the wire?

• A

• B

• C

• D

A copper wire X has resistance R. Another copper wire Y has twice the length and half the cross- sectional area of X.

What is the resistance of Y?

• R/2

• R

• 2R

• 4R

An electrical appliance is plugged into a socket in the wall. The plug contains a fuse. What is the main purpose of the fuse?

• to earth the appliance

• to earth the plug

• to protect the user from electric shock

• to protect the wiring from overheating

The diagram shows a set of apparatus used to determine the specific heat capacity of water.

What does not affect the rate at which energy is lost to the surroundings?

• insulating the container

• placing a lid on the container

• polishing the outer surface of the container

• moving the thermometer closer to the heater

Two thermometers X and Y contain different liquids but are otherwise identical.

The thermometers are heated through the same temperature rise. The volume of liquid in thermometer X increases by more than the volume of liquid in thermometer Y.

Which is the more sensitive thermometer and which is the thermometer with the larger range?

• A

• B

• C

• D

The diagram shows air trapped in a flask by a small volume of water in a thin tube.

When the flask is held in a student’s hands, the small volume of water first moves down from P to Q, and then up to R.

Why does the small volume of water move like this?

• The flask contracts and then the air expands.

• The flask expands and then the air contracts.

• The flask expands and then the air expands less than the flask.

• The flask expands and then the air expands more than the flask.