S2M2 - PHYSICS 12

The student then holds the plastic rod near to a stream of water coming from a tap.

The stream of water bends towards the plastic rod as shown below.

Which picture shows the correct arrangement of charges in the stream of water?

• A

• B

• C

• D

A plastic rod and a piece of cloth are both uncharged.

A student rubs the plastic rod with the cloth.

The plastic rod becomes negatively charged.

Compared with the plastic rod, which row of the table is correct for the charge on the cloth?

• A

• B

• C

• D

An electrostatic air filter is designed to remove dust particles from the air in a room.

A fan blows dusty air past several metal rods and metal plates.

There is a large potential difference (voltage) between the metal rods and the metal plates.

When dusty air goes past the metal rods, the dust particles become negatively charged.

This is because the dust particles

• lose electrons

• lose protons

• gain electrons

• gain protons

A student ties two balloons to a support with some string.

the student rubs both balloons with a dry cloth which gives the balloons a negative charge.

The diagram shows the balloons after they were rubbed. Hence, we can conclude that

"The balloons _______ each other because they have the same _______"

• attracted, charge

• repelled, charge

• attracted, elecrtons

• repelled, protons

The diagram shows an electrostatic insecticide spray being used on a plant.

The plant is initially uncharged.

Each droplet of spray is given a positive charge.

What is the advantage of using this spray?

• it prevents insecticides being wasted as it is attracted to the plant's leaves while being sprayed.

• it gives better growth and development to plants due to its electrostatic effect.

• the accumulation of charges on the plant's leaves will induce the growth hormones of the plants.

• the charged insecticide is much cheaper than the uncharged one.

A student rubs a plastic rod with a dry cloth. The cloth becomes positively charged.

The cloth becomes positively charged because.

• negative charge has moved from the cloth to the rod.

• negative charge has moved from the rod to the cloth.

• positive charge has moved from the cloth to the rod.

• positive charged has moved from the rod to the cloth.

Two plastic strips are joined at the top and are hanging by a thread.

The student rubs both strips with another dry cloth.

The diagram shows the two plastic strips before and after the student rubs them.

Explain why the strips behave in this way after they are rubbed with the cloth.

• both strips have gained equal but opposite charges

• both strips have lose equal but oppositve charges

• both strips have gained equal amount of charges

• both strips have lose equal amount of electrons.

Direct current is movement of charge

• backwards and forwards

• in many directions

• in one direction

• up and down

The current in a wire is 3.7 A.

Calculate the charge that flows into the wire in 13 s.

• 0.28 C/s

• 3.5 s/C

• 16.7 C.s

• 9.3 C.s

A technician investigates a light-dependent resistor (LDR) connected in series with a 120 ohm resistor and a voltage source.

The technician measures the voltage across the LDR and also the current in the LDR.

Which one of these circuits should the technician use?

• A

• B

• C

• D