Ray Optics and Optical Instruments — Physics STD 12 Science — Question

The temperature coefficient of resistance of a conductor is (a) Positive always(b) Negative always(c) Zero  (d) Infinite

A radioactive substance emits(a) Electromagnetic radiation(b) Electrons revolving around the nucleus(c) Charged particles(d) a,c

If the central portion of a convex lens is wrapped in black paper as shown in the figure

A liquid can easily change its shape but a solid can not because.

1. The density of a liquid is smaller than that of a solid.
2. The forces between the molecules is stronger in solid than in liquids.
3. The atoms combine to form bigger molecules in a solid.
4. The average separation between the molecules is larger in solids.

The limit of resolution of eye is approximately:

According to the pulsating theory the expansion and contraction of the universe repeats after every (a) 11 years(b) 8 billion years(c) 8 million years(d) 80 billion years

Resistance of the conductor depends upon:

Pick the correct options.

1. All electrons have magnetic moment.
2. All protons have magnetic moment.
3. All nuclei have magnetic moment.
4. All atoms have magnetic moment.

At a place, if the earth's horizontal and vertical components of magnetic fields are equal, then the angle of dip will be(a) 30°(b)  90°(c) 45° (d)  0°