Electromagnetic Waves — Physics STD 12 Science — Question

Which of the following curves may represent the speed of the electron in a hydrogen atom as a function of the principal quantum number n?

A gas is contained in a metallic cylinder fitted with a piston. The piston is suddenly moved in to compress the gas and is maintained at this position. As time passes the pressure of the gas in the cylinder:

1. Increases.
2. Decreases.
3. Remains constant.
4. Increases or decreases depending on the nature of the gas.

An elementary particle of mass  m and charge +e  is projected with velocity v at a much more massive particle of charge Ze,  where Z > 0. What is the closest possible approach of the incident particle

(a)

(b)

(c)

(d)

Three identical resistances A, B and C are connected as shown in the given figure. The heat produced will be maximum

(a) In B

(b) In B and C

(c) In A

(d) Same for A, B and C

If the work function for a certain metal is 3.2  joule and it is illuminated with light of frequency 8  Hz. The maximum kinetic energy of the photo-electrons would be (h = 6.63

(a) 3.2

(b) 8.5

(c) 5.3

(d) 3.2

Which of the following parameters are the same for all hydrogen-like atoms and ions in their ground states?

1. Radius of the orbit.
2. Speed of the electron.
3. Energy of the atom.
4. Orbital angular momentum of the electron.

Viscosity is a property of:

1. Liquids only.
2. Solids only.
3. Solids and liquids only.
4. Liquids and gases only.

The resistance of a coil is 4.2 Ω at 100 ^oC and the temperature coefficient of resistance of its material is 0.004/^o C.  Its resistance at 0^o C is

(a) 6.5 Ω

(b) 5 Ω

(c) 3 Ω

(d) 4 Ω

The energy of hydrogen atom in its ground state is – 13.6 eV. The energy of the level corresponding  to the quantum number n is equal 5 is

(a) – 5.40 eV

(b) – 2.72 eV

(c) – 0.85 eV

(d) – 0.54 eV

If the magnetic field of an electromagnetic wave is given as B_{y ​}= 2 × 10^-7 sin(10³x + 1.5 × 10¹²t) tesla, the wavelength of the electromagnetic wave is.