Two simple pendulums A and B are made to oscillate simultaneously and it is found that A completes 10 oscillations in 20 sec and B completes 8 oscillations in 10 sec. The ratio of the length of A and B is

• $\frac{25}{64}$

• $\frac{64}{25}$

• $\frac{8}{5}$

• $\frac{5}{4}$

The waves set up in a closed pipe are

• longitudinal and progressive

• transverse and progressive

• transverse and stationary

• longitudinal and stationary

'Young's modulus' is defined as the ratio of

• hydraulic stress and hydraulic strain

• shearing stress and shearing strain

• tensile stress and longitudinal strain

• bulk stress and longitudinal strain

A piece of copper is to be shaped into a conducting wire of maximum resistance. The suitable length and diameter are respectively

• 2L and d/2

• L/2 and 2d

• L and d

• 2L and d

'Hydraulic lift' works on the basis of

• Stoke's Law

• Bernoulli's Law

• Pascal's Law

• Toricelli's Law

The mean energy of a molecule of an ideal gas is

• $\frac{1}{2} \mathrm{KT}$

• 2 KT

• KT

• $\frac{3}{2} \mathrm{KT}$

A coil of inductive reactance $1/\sqrt{3} \mathrm{\Omega }$ and resistance 1 Ω is connected to a 200 V, 50 Hz AC supply. The time lag between maximum voltage and current is

• $\frac{1}{200} \mathrm{s}$

• $\frac{1}{300} \mathrm{s}$

• $\frac{1}{500} \mathrm{s}$

• $\frac{1}{600} \mathrm{s}$

18.

Of the following graphs, the one that correctly represents the I-V characteristics of a 'Ohmic device' is

• 

• 

• 

• 

The susceptibility of a ferromagnetic substance is

• Zero

• > 1

• < 1

• >> 1

The working of magnetic braking of trains is based on

• eddy current

• pulsating current

• alternating current

• steady current