Is a mirror always a direct reflection of the real object?

The power of a lens is -2.0 D. Here ‘D’ stands for ________.

What is the kilowatt hour unit?

The instrument that measures and records the relative humidity of air is:

What is the unit of magnetic field?

Which one of the following common devices works on the basis of the principle of mutual induction?

What type of current is obtained from dynamo?

Instrument for measuring blueness of the sky or ocean is called ___________.