Which one among the following is the correct value of the gravitational force of the Earth acting on a body of mass 1kg?

• 8.9 N

• 9.8 N

• 89 N

• 98 N

A neutral (unchanged) metal ball is suspended using a non-magnetic string. A positively charged insulating rod is placed near the ball which is observed to be attracted to the rod. This is because

• the ball becomes positively charged by induction

• the ball becomes negatively charged by induction

• there is a rearrangement of the electrons in the ball

• the number of electrons in the ball is more than the number of electrons on the rod

It is impossible for two oscillators, each executing simple harmonic motion, to remain in phase with each other if they have different

• time periods

• amplitudes

• spring constants

• kinetic energy

The potential at a point due to a point charge is V. The charge is doubled and also the distance of the point from the charge is doubled. The new potential is

• V/2

• 4V

• V

• 2V

Which one among the following is used to make periscope?

• Concave lens

• Concave mirror

• Plane mirror

• None of the above

Kilowatt-hour is the unit of

• potential difference

• electric power

• electric energy

• electric potential

What is the power of the lens, if the far point of a short-sighted eye is 200 cm?

• -0.5 D

• 2 D

• 1 D

• -1.5 D

Which one among the following is correct for the resultant of balanced forces?

• It is zero

• It is non-zero

• It varies continuously

• None of the above

Three resistance coils of 1Ω, 2Ω, and 3Ω are connected in series. If the combination is connected to a battery of 9 V, what is the potential drop across the resistance coil of 3Ω?

• 2.0 volt

• 3.0 volt

• 4.5 volt

• 6.0 volt

310.

An electric lamp of 100 watts is used for -10 hours per day. The 'units' of energy consumed in one day by the lamp is

• 1 unit

• 0.1 unit

• 10 units

• 100 units