Electromagnetic Induction — Physics STD 12 Science — Question

A direct X-ray photograph of the intestines is not generally taken by the radiologists because (a) Intestines would burst on exposure to X-rays(b) The X-rays would not pass through the intestines(c) The X-rays will pass through the intestines without causing a good shadow for any useful diagnosis(d) A very small exposure of X-rays causes cancer in the intestines

Consider the two idealised systems: (i) a parallel plate capacitor with large plates and small separation and (ii) a long solenoid of length L > > R, radius of cross-section. In (i), E is ideally treated as a constant between plates and zero outside. In (ii), magnetic field is constant inside the solenoid and zero outside. These idealised assumptions, however, contradict fundamental laws as below:

Assertion  :  Thin films such as soap bubble or a thin layer of  oil on water show beautiful colours when illuminated by white light.
 Reason     : It happens due to the interference of light reflected from the upper surface of the thin film. (a) If both assertion and reason are true and the reason is the correct explanation of the assertion.(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.(c) If assertion is true but reason is false.(d) If the assertion and reason both are false.

A photo sensitive metal is not emitting photo-electrons when irradiated. It will do so when threshold is crossed. To cross the threshold we need to increase?

Let p and E denote the linear momentum and energy of a photon. If the wavelength is decreased:

1. Both p and E increase.
2. P increases and E decreases.
3. P decreases and E increases.
4. Both p and E decrease.

Which of the following principle is used in optical fibre?

A coil of inductance L is carrying a steady current i. What is the nature of its stored energy(a)  Magnetic(b)  Electrical(c)  Both magnetic and electrical(d)  Heat