Wave Optics — Physics STD 12 Science — Question

A convex mirror of focal length f forms an image which is   times the object. The distance of the object from the mirror is

(a) (n – 1)f

(b)

(c)

(d) (n + 1)f

The impurity atoms with which pure silicon may be doped to make it a p-type semiconductor are those of:

1. Phosphorus.
2. Boron.
3. Antimony.
4. Aluminium.

Two waves of same amplitude and same wavelength are superimposed in different phases. The amplitude of the resultant wave will be maximum when the phase difference between them is:

The formula of torque due to electric dipole is:

Consider the two idealized systems: (i) a parallel plate capacitor with large plates and small separation and (ii) a long solenoid of length L > > R, radius of cross-section. In (i) E is ideally treated as a constant between plates and zero outside. In (ii) magnetic field is constant inside the solenoid and zero outside. These idealised assumptions, however, contradict fundamental laws as below:

The correct relation is (Where  Horizontal component of earth's magnetic field;  = Vertical component of earth's magnetic field and B  = Total intensity of earth's magnetic field)

(a) B =

(b)

(c) |B| =

(d)

If resistance of voltmeter is 10000 W and resistance of ammeter is 2 W then find R when voltmeter reads 12V and ammeter reads 0.1 A

(a) 118 W

(b) 120 W

(c) 124 W

(d) 114W

If an observer is walking away from the plane mirror with 6m/sec.  Then the velocity of the image with respect to observer will be

(a) 6 m/sec

(b) -6 m/sec

(c) 12 m/sec

(d) 3 m/sec