Alternating Current — Physics STD 12 Science — Question

In H -atom the radius of electron's first orbit in A will be :

A convex lens is in contact with concave lens. The magnitude of the ratio of their focal length is 2/3. Their equivalent focal length is 30 cm. What are their individual focal lengths

(a) – 75, 50

(b) – 10, 15

(c) 75, 50

(d) – 15, 10

A conducting loop is kept in a uniform magnetic field such that its plane is perpendicular to the magnetic field. Induced emf will be generated in the loop if:

1 electron volt = __________ J.

What is the net electric field in the outer regions above the upper plate and below the lower plate in a parallel plate capacitor?

The self inductance of a coil is 5 henry, a current of 1 amp change to 2 amp within 5 second through the coil. The value of induced e.m.f. will be

(a) 10 volt

(b) 0.10 volt

(c) 1.0 volt

(d) 100 volt

The power factor of L-R circuit is :

Which of the following gates will have an output of 1

(a) (a)

(b)

(c)

(d)

As shown in the figure, a very thin sheet of aluminium is placed in between the plates of the condenser. Then the capacity

(a) Will increase	(b) Will decrease
(c) Remains unchanged	(d) May increase or decrease

The electric field in a region is directed outward and is proportional to the distance r from the origin. Taking the electric potential at the origin to be zero,