Conductors of Heat and Electricity (Grade 5)

1. The handles of our cooking utensils at home are usually made of rubber or hard plastics that do not allow heat to pass through them. These materials

• have high resistance

• are conductors

• both a and b

• Neither a or b

Which of the following materials does not belong to the group?

• rubber slippers

• ceramic plate

• aluminum frying pan

• electrical tape

Which of the following materials are likely to exhibit more conductive properties than insulating properties?

• rubber

• aluminum

• silver

• plastic

• wet skin

Electricians usually wear rubber gloves for protection. The purpose of the rubber gloves is to

• keep the electrician dry

• create an electrical circuit

• produce electricity

• insulate the electrician

Many electrical wires are wrapped with a plastic coating because plastic is

• less expensive than steel

• denser than copper

• able to keep its shape

• a good insulator

The inside of a solar cooker and the pipes of a solar water heater are painted black because black surface is a

• Good reflector of heat

• Good absorber of heat

• Poor absorber of heat

• Good radiator of heat

A cement floor would feel cold as compared to a wooden one on a cold morning because the cemented floor

• is a better conductor of heat than the wooden floor.

• is polished while wooden floor is not polished.

• reflects more heat than wooden floor.

• is a poor conductor of heat than the wooden floor.

We usually see street dwellers lying on flattened carton boxes and wrapping themselves with a few layers of newspaper on a cold night. This helped them to keep themselves warm because

• Friction between the layers of newspaper produces heat.

• Air trapped between the layers of newspaper is a bad conductor of heat.

• Newspaper is a conductor of heat.

• Newspaper is at a higher temperature than the temperature of the surrounding.

Which of these objects is opaque?

• a brick wall

• eyeglasses lenses

• liquid water

• stained glass windows

Which part of an automobile is transparent?

• door handle

• side mirror

• hubcap

• windshield