A sonometer wire 100 cm long has a fundamental frequency of 330 Hz. The velocity of propagation of transverse waves on the wire is

• 330 ms^-1

• 660 ms^-1

• 990 ms^-1

• 115 ms^-1

A glass tube of length 1.0 m is completely filled with water. A vibrating tuning fork of frequency 500 Hz is kept over the mouth of the tube and the water is drained out slowly at the bottom of the tube. If velocity of sound in air is 330 ms^-1, then the total number of resonances that occur will be

• 2

• 3

• 1

• 5

A bus is moving with a velocity of 5 ms^-1 towards a huge wall. The driver sounds a horn of frequency 165 Hz. If the speed of sound in air is 335 ms^-1, the number of beats heard per second by a passenger inside the bus will be

• 3

• 4

• 5

• 6

34.

The current I through 10 Ω resistor in the circuit given below is

           

• 50 mA

• 20 mA

• 40 mA

• 80 mA

The resonance frequency of the tank circuit of an oscillator when $\mathrm{L} = \frac{10}{{\mathrm{\pi }}^2} \mathrm{mH}$ and C = 0.04 µF are connected in parallel is

• 250 kHz

• 25 kHz

• 2.5 kHz

• 25 MHz

Millikan's oil-drop experiment established that

• electric charge depends on velocity

• specific charge of electron is 1.76 x 10¹¹ Ckg^-1

• electron has wave nature

• electric charge is quantized

Two identical conducting spheres carrying different charges attract each other with a force F when placed in air medium at a distance d apart. The spheres are brought into contact and then taken to their original positions. Now the two spheres repel each other with a force whose magnitude is equal to that of the initial attractive force.The ratio between initial charges on the spheres is 

• $- \left(3 + \sqrt{8}\right) \mathrm{only}$

• $- 3 + \sqrt{8} \mathrm{only}$

• $- \left(3 + \sqrt{8}\right) \mathrm{or} \left(-3 + \sqrt{8}\right)$

• $+ \sqrt{3}$

Small drops of the same size are charged to V volt each. If n such drops coalesce to form a single large drop, its potential will be

• Vn

• V/n

• Vn^1/3

• Vn^2/3

A capacitor of capacitance value 1 µF is charged to 30 V and the battery is then disconnected. If the remaining circuit is connected across a 2 µF capacitor, the energy lost by the system is

• 300 µJ

• 450 µJ

• 225 µJ

• 150 µJ

An electric dipole of length 1 cm is placed with the axis making an angle of 30° to an electric field of strength 10⁴ NC^-1. If it experiences a torque of $10\sqrt{2} \mathrm{Nm}$ Nm, the potential energy of the dipole is

• 0.245 J

• 2.45 × 10^-4 J

• 24.5 × 10^-4 J

• 245.0 J