Electric Charges and Fields — Physics STD 12 Science — Question

In the given circuit if point C is connected to the earth and a potential of +2000 V  is given to the point A, the potential at B is

(a) 1500 V

(b) 1000 V

(c) 500 V

(d) 400 V

A block A kept on an inclined surface just begins to slide if the inclination is 30°. The block is replaced by another block B and it is found that it just begins to slide if the inclination is 40°:

1. Mass of A > mass of B.
2. Mass of A < mass of B.
3. Mass of A = mass of B.
4. All the three are possible.

If a positive charge is shifted from a low-potential region to a high-potential region, the electric potential energy.

As compared ¹²C atom, ¹⁴C atom has

(a) Two extra protons and two extra electrons

(b) Two extra protons but no extra electrons

(c) Two extra neutrons and no extra electrons

(d) Two extra neutrons and two extra electrons

Let F, F_N and f denote the magnitudes of the contact force, normal force and the friction exerted by one surface on the other kept in contact. If none of these is zero:

1. F > F_N
2. F > f
3. F_N > f
4. F_N - f < F < F_N + f

An expression for rate of heat generated, if a current of I ampere flows through a resistance of R W, is

(a)

(b)

(c)

(d) IR

A current of two amperes is flowing through a cell of e.m.f. 5 volts and internal resistance 0.5 ohm from negative to positive electrode. If the potential of negative electrode is 10V, the potential of positive electrode will be

(a) 5 V

(b) 14 V

(c) 15 V

(d) 16 V

The capacitor of capacitance 4 μF  and 6 μF  are connected in series. A potential difference of  500 volts is applied to the outer plates of the two capacitor system. The potential difference across the plates of capacitor of 4 μF  capacitance is

(a) 500 volts

(b) 300 volts

(c) 200 volts

(d) 250 volts

Two identical parallel plate capacitors are connected in series to a battery of 100 V. A dielectric slab of dielectric constant 4.0 is inserted between the plates of second capacitor.  The potential difference across the capacitors will now be respectively

(a) 50 V, 50 V

(b) 80 V, 20 V

(c) 20 V, 80 V

(d) 75 V, 25 V

A P-type semiconductor has acceptor levels 57 meV above the valence band. The maximum wavelength of light required to create a hole is (Planck’s constant h = 6.6  J-s)

(a) 57

(b) 57

(c) 217100

(d) 11.61