Electromagnetic Induction — Physics STD 12 Science — Question

In the hydrogen atom, an electron makes a transition from n = 2 to n = 1. The magnetic field produced by the circulating electron at the nucleus?

A hydrogen atom in its ground state absorbs 10.2 eV of energy. The orbital angular momentum is increased by (Given Planck constant h = 6.6 J - sec)

(a) 1.05   J-sec

(b) 3.16   J-sec

(c) 2.11   J-sec

(d) 4.22   J-sec

A double convex lens of focal length 20 cm is made of glass of refractive index 3 / 2. When placed completely in water (a,  its focal length will be

(a) 80 cm

(b) 15 cm

(c) 17.7 cm

(d) 22.5 cm

The potentials of the two plates of capacitor are +10V and –10 V. The charge on one of the plates is 40 C. The capacitance of the capacitor is

(a) 2 F

(b) 4 F

(c) 0.5 F

(d) 0.25 F

A medium is said to be dispersive, if

(a) Light of different wavelengths propagate at different speeds

(b) Light of different wavelengths propagate at same speed but has different frequencies

(c) Light is gradually bent rather than sharply refracted at an interface between the medium and air

(d) Light is never totally internally reflected

The ripple factor in a half wave rectifier is

(a) 1.21

(b) 0.48

(c) 0.6

(d) None of these

The force that a unit positive charge would experiences if placed at that point is called as _____ due to charge at a point in space.

A short magnet of moment 6.75 Am² produces a neutral point on its axis. If horizontal component of earth's magnetic field is 5  , then the distance of the neutral point should be

(a) 10 cm

(b) 20 cm

(c) 30 cm

(d) 40 cm

The air film in a Newton's ring apparatus is replaced by an oil film. The radii of the rings: