Atoms — Physics STD 12 Science — Question

In a transformer the primary has 500 turns and secondary has 50 turns. 100 volts are applied to the primary coil, the voltage developed in the secondary will be

(a) 1 V

(b) 10 V

(c) 1000 V

(d) 10000 V

In Young's double-slit experiments, a monochromatic light source is used. The shape of interference fringes produced on screen will be :

A man runs towards mirror at a speed of 15 m/s. What is the speed of his image

(a) 7.5 m/s

(b) 15 m/s

(c) 30 m/s

(d) 45 m/s

In summer, a mild wind is often found on the shore of a calm river. This is caused due to,

1. Difference in thermal conductivity of water and soil.
2. Convection currents.
3. Conduction between air and the soil.
4. Radiation from the soil.

A charged particle oscillates about its mean equilibrium position with a frequency of 10⁹Hz. The electromagnetic waves produced:

When a hot liquid is mixed with a cold liquid, the temperature of the mixture:

1. First decreases then becomes constant.
2. First increases then becomes constant.
3. Continuously increases.
4. Is undefined for some time and then becomes nearly constant.

The mean electric energy density between the plates of a charged capacitor is (here q = charge on the capacitor and  A = area of the capacitor plate)

(a)

(b)

(c)

(d) None of the above

In Millikan oil drop experiment, a charged drop of mass 1.8   is stationary between its plates. The distance between its plates is 0.90 cm and potential difference is 2.0 kilo volts. The number of electrons on the drop is

(a) 500

(b) 50

(c) 5

(d) 0

An electron changes its position from orbit n = 4 to the orbit n = 2  of an atom. The wavelength of the emitted radiation’s is (R = Rydberg’s constant)

(a)

(b)

(c)

(d)