Electromagnetic Waves — Physics STD 12 Science — Question

A hydrogen atom in its ground state absorbs 10.2 eV of energy. The orbital angular momentum is increased by

(a) 1.05   J-sec

(b) 3.16   J-sec

(c) 2.11   J-sec

(d) 4.22   J-sec

Number of electrons in one coulomb of charge will be

(a) 5.46

(b)  6.25

(c) 1.6

(d) 9

Work of electric motor is

(a) To convert ac into dc	(b) To convert dc into ac
(c) Both (a) and (b)	(d) To convert ac into mechanical work

Hydrogen atoms are excited from ground state of the principal quantum number 4. Then the number of spectral lines observed will be

(a) 3

(b) 6

(c) 5

(d) 2

For measurement of potential difference, potentiometer is preferred in comparison to voltmeter because

(a) Potentiometer is more sensitive than voltmeter

(b) The resistance of potentiometer is less than voltmeter

(c) Potentiometer is cheaper than voltmeter

(d) Potentiometer does not take current from the circuit

A particle is projected in a plane perpendicular to a uniform magnetic field. The area bounded by the path described by the particle is proportional to:

1. The velocity.
2. The momentum.
3. The kinetic energy.
4. None of these.

A current passes through a resistor. If K₁ and K₂ represent the average kinetic energy of the conduction electrons and the metal ions respectively then:

Water flows through two identical tubes A and B. A volume V₀ of water passes through the tube A and 2 V₀ through B in a given time. Which of the followinmay be correct?

1. Flow in both the tubes are steady.
2. Flow in both the tubes are turbulent.
3. Flow is steady in A but turbulent in B.
4. Flow is steady in B but turbulent in A.

Which of the following phenomena can explain quantum nature of light

(a) Photoelectric effect

(b) Interference

(c) Diffraction

(d) Polarisation

The condition for a uniform spherical mass m of radius r to be a black hole is [G = gravitational constant and g = acceleration due to gravity]

(a)

(b)

(c)

(d)