Alternating Current — Physics STD 12 Science — Question

An astronaut in a spaceship see the outer space as(a) White (b) Black(c) Blue(d) Red

For which of the following colour, the magnifying power of a microscope will be maximum(a) White colour (b)  Red colour (c) Violet colour (d)  Yellow colour 

Consider the following statements:

1. An emf can be induced by moving a conductor in a magnetic field.
2. An emf can be induced by changing the magnetic field.

What is the resistance of a carbon resistance which has bands of colours brown, black and brown

A long, straight wire carries a current i. The magnetizing field intensity H is measured at a point P close to the wire. A long, cylindrical iron rod is brought close to the wire so that the point P is at the centre the rod. The value of H at P will:

1. Increase many times.
2. Decrease many times
3. Remain almost constant.
4. Become zero.

A lens behaves as a converging lens in air and a diverging lens in water. The refractive index of the material is(a) Equal to unity(b) Equal to 1.33(c) Between unity and 1.33(d) Greater than 1.33

Identify the direction in which a thin long piece of magnet comes to rest when suspended freely.

The value of angle of dip is zero at the magnetic equator because on it(a) V and H are equal(b) The value of V and H is zero(c) The value of V is zero(d) The value of H is zero