If work done in increasing the size of a soap film from 10 cm x 6 cm to 10 cm x 11 cm is 2x10-4 J, then surface tension is
2x10-2 Nm-1
2x10-4 Nm-1
2x10-6 Nm-1
2x10-8 Nm-1
A battery of emf 10 V and internal resistance 3 Ω is connected to a resistor. The current in the circuit is 0.5 A. The terminal voltage of the battery when the circuit is closed is
10 V
zero
1.5 V
8.5 V
A galvanometer coil has a resistance of 15 Ω and gives full-scale deflection for a current of 4 mA. To convert it to an ammeter of range 0 to 6 A
10 mΩ resistance is to be connected in parallel to the galvanometer
10 mΩ resistance is to be connected in series with the galvanometer
0.1 Ω resistance is to be connected in parallel to the galvanometer
0.1 Ω resistance is to be connected in series with the galvanometer
A Gaussian sphere encloses an electric dipole within it. The total flux across the sphere is
zero
half that due to a single charge
double that due to a single charge
dependent on the position of the dipole
A parallel plate air capacitor has a capacitance C. When it is half-filled with a dielectric of dielectric constant 5, the percentage increase in the capacitance will be
400%
66.6%
33.3%
200%
B.
66.6%
initial capacitance C =
When it is half-filled by a dielectric constant K, then
and
hence, increase in capacitance
= 5/3 - 1 = 2/3
= 66.6%
The specific charge of a proton is 9.6 x107 C kg-1 The specific charge of an alpha particle will be
9.6 x107 C kg-1
19.2 x107 C kg-1
4.8 x107 C kg-1
2.4 x107 C kg-1
A gang capacitor is formed by interlocking a number of plates as shown in the figure.The distance between the consecutive plates is 0.885 cm and the overlapping area of the plates is 5 cm. The capacity of the unit is
1.06 pF
4 pF
6.36 pF
12.72 pF
A battery consists of a variable number (n) of identical cells, each having an internal resistance r connected in series. The terminals of the battery are short-circuited. A graph of current (I) in the circuit versus the number of cells will be as shown in figure
In a LCR series circuit, the potential difference between the terminals of the inductance is 60 V, between the terminals of the capacitor, is 30 V and that across the resistance is 40 V. Then, the supply voltage will be equal to
50 V
70 V
130 V
10 V
A solenoid 1.5 m long and 0.4 cm in diameter possesses 10 turns/cm length. A current of 5 A falls through it. The magnetic field at the axis inside the solenoid is
2π × 10-3 T
2π × 10-5 T
4π × 10-2 T
4π × 10-3 T