Magnetic keepers are pieces of soft iron that are placed across the poles of a bar magnet or a horseshoe magnet. They help prevent the loss of magnetism.

Correct Option: D

Magnetic keepers are pieces of soft iron that are placed across the poles of a bar magnet or a horseshoe magnet. They help prevent the loss of magnetism.

The earth’s surface radiates as a black body, since it aborts and radiates with nearly 100 percent efficiency for its temperatures. Gases, on the contrary, are selective absorbers and radiators.

Correct Option: C

The earth’s surface radiates as a black body, since it aborts and radiates with nearly 100 percent efficiency for its temperatures. Gases, on the contrary, are selective absorbers and radiators.

X-rays – smaller than 10 nano metre gamma- rays – 0.0005 to 0.1 nano metre alpha-rays – 125 nano metre

Correct Option: C

X-rays – smaller than 10 nano metre gamma- rays – 0.0005 to 0.1 nano metre alpha-rays – 125 nano metre

Convex mirrors are used as rear view mirrors in automobiles to see the traffic on the rear side. A convex mirror always produces an erect image of the objects. The image formed in a convex mirror is highly diminished than the object, due to which a convex mirror gives a wide field of view of the traffic behind.

Correct Option: D

Convex mirrors are used as rear view mirrors in automobiles to see the traffic on the rear side. A convex mirror always produces an erect image of the objects. The image formed in a convex mirror is highly diminished than the object, due to which a convex mirror gives a wide field of view of the traffic behind.

In a water lifting electric pump, we convert electrical energy into potential energy. In hydraulic pump mechanical energy in converted into potential energy.

Correct Option: A

In a water lifting electric pump, we convert electrical energy into potential energy. In hydraulic pump mechanical energy in converted into potential energy.