Quick Physics Evaluation

A resistance of 20 ohm is connected to a source of an alternating potential V=220 sin (100 πt). The time taken by the current to change from its peak value to r.m.s value is

The radius of a nucleus of mass number A is directly proportional to

If oxygen has root mean square velocity of C m/s, then root mean square velocity of hydrogen will be

The drift velocity does not depend upon

The shortest wavelength in Lyman series is 91.2 nm. The largest wavelength of the series is

The magnetic flux linked with a coil at any instant t is given by ?= (5t³ – 100t + 300). The e.m.f induced in the coil at t=2 sec is

The frequencies of X-rays,γ-rays and ultraviolet rays are respectively p,q and r, then

When npn transistor is used as an amplifier

A sample of HCl gas is placed in an electric field of 5 x 10⁴ N/C. The dipole moment of each HCl molecule is 6 x 10⁻³⁰ Cm. The maximum torque that can act on a molecule is

A body revolved around the sun 27 times faster than the earth. What is the ratio of their radii?

If rope of lift breaks suddenly, the tension exerted by the surface of the lift (a = Acceleration of lift) is

The angular momentum of an electron is J. The magnitude of the magnetic moment will be

A projectile is fired at 30°. Neglecting friction, the change in kinetic energy when it returns to the ground will be

A body travels 200 cm in the first two seconds and 220 cm in the next 4 secs with deceleration. The velocity of the body at the end of the 7th second is

The total kinetic energy of a body of mass 10 kg and radius 0.5 m moving with a velocity of 2 m/s without slipping is 32.8 J. The radius of gyration of the body is

The displacement of a particle varies according to the relation x=4 (cos π t + sin π t). The amplitude of the particle is

The dimensional formula of Plancks’s constant and angular momentum are

Surface tension of a solution is 30 x 10⁻² N/m. The radius of the soap bubble is 5 cm. The surface energy of soap bubble is

A radioactive substance contains 10000 nuclei and its halflife period is 20 days. The number of nuclei present at the end of 10 days is

The radius of the convex surface of a plano-convex lens is 20 cm and the refractive index of material of the lens is 1.5. The focal length of lens is

540 g of ice at 0° C is mixed with 540 g of water at 80° C. The final temperature of the mixture in °C will be

If the sodium light in Young’s double slit experiment is replaced by red light, the fringe width will

Two identical flutes produce fundamental notes of frequency 300 Hz at 27° C. If the temperature of air in one flute is increased to 31° C, the number of beats heard per sec will be

In stretching a spring by 2 cm, energy stored is given by U. Had is been stretched by 10 cm, energy stored will be