A bar magnet is equivalent to _______.

How many times more intense is a 60 dB sound than a 30 dB sound?

Hydrogen atom does not emit X-rays because

If an electron and a proton have the same de-Broglie wavelength, then the kinetic energy of the electron is

In an unbiased p-n junction

Maximum diffraction takes place in a given slit for

Pick out the correct statement from the following :

Pick out the statement which is NOT correct.

Solar spectrum is an example for

The most stable particle in Baryon group is

The spectrum of an oil flame is an example for _____.

A convex and a concave lens seperated by distance d are then put in contact. The focal length of the combination

A charge Q is enclosed by a Gaussian spherical surface of radius R. If the radius is doubled, then the outward electric flux will

A convex lens of focal length 30 cm produces 5 times magnified real image of an object. What is the object distance?

According to Einstein's photoelectric equation, the graph of K.E. of the photoelectron emitted from the metal versus the frequency of the incident radiation gives a straight line graph, whose slope ______.

An astronaut on a strange planet finds that acceleration due to gravity is twice as that on the surface of Earth. Which of the following could explain this?

Electromagnetic wave consists of periodically oscillating electric and magnetic vectors ______.

For a series LCR circuit at resonance, the statement which is not true is

Hot water cools from 60°C to 50°C in the first 10 minutes and to 42°C in the next 10 minutes. Then the temperature of the surroundings is _____.