Alternating Current — Physics STD 12 Science — Question

A charge of   is placed on each of the 64 identical drops of radius 2cm. They are then combined to form a bigger drop. Find its potential             

(a) 7.2

(b) 7.2

(c) 1.44

(d) 1.44

The charge given to a hollow sphere of radius 10 cm is 3.2 × 10^–19 coulomb. At a distance of 4 cm from its centre, the electric potential will be

(a) 28.8 ×

(b) 288 volts

(c) 2.88 volts

(d) Zero

Two identical capacitors A and B are charged to the same potential V and are connected in two circuits at t = 0 as shown in figure. The charges on the capahltors at a time t = CR are, respectively:

An eye specialist prescribes spectacles having a combination of convex lens of focal length 40 cm in contact with a concave lens of focal length 25 cm. The power of this lens combination in diopters is

(a) + 1.5

(b) – 1.5

(c) + 6.67

(d) – 6.67

A rigid container of negligible heat capacity contains one mole of an ideal gas. The temperature of the gas increases by 1°C if 3.0cal of heat is added to it. The gas may be:

1. Helium.
2. Argon.
3. Oxygen.
4. Carbon dioxide.

In an ideal parallel LC circuit, the capacitor is charged by connecting it to a D.C. source which is then disconnected. The current in the circuit.

On decreasing the distance between the plates of a parallel plate capacitor, its capacitance:

A problem of practical interest is to make a beam of electrons turn at 90° corner. This can be done with the parallel plates shown in figure. An electron with kinetic energy 8.0 × 10^-17J enters through a small hole in the bottom plate. The strength of electric field that is needed if the electron is to emerge from an exit hole 1.0cm away from the entrance hole, traveling at right angles to its original direction is _______ ×10⁵N/ C.

An electron and a proton with equal momentum enter perpendicularly into a uniform magnetic field, then

(a) The path of proton shall be more curved than that of electron

(b) The path of proton shall be less curved than that of electron

(c) Both are equally curved

(d) Path of both will be straight line