Atoms — Physics STD 12 Science — Question

The cut-in voltage for silicon diode is approximately

(a) 0.2 V

(b) 0.6 V

(c) 1.1 V

(d) 1.4 V

Three charges each of magnitude q are placed at the corners of an equilateral triangle, the electrostatic force on the charge placed at the center is (each side of triangle is L)

(a) Zero

(b)

(c)

(d)

When an electric field is applied across a semiconductor:

Unlike charges _____ each other.

The wavelength of  X-rays produced by an X-ray tube is 0.76 Å. The atomic number of the anode material of the tube is

(a) 20

(b) 60

(c) 40

(d) 80

The curve of binding energy per nucleon as a function of atomic mass number has a sharp peak for helium nucleus. This implies that helium?

Which of the following reaction must be initiated by the neutron?

The peak voltage in a 220V AC source is:

1. 220V.
2. About 160V.
3. About 310V.
4. 440V.

Assertion  : Amongst alpha, beta and gamma rays, a-particle has maximum penetrating power.

Reason      : The alpha particle is heavier than beta and gamma rays.

(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 wire has a resistance of 12 ohm. It is bent in the form of equilateral triangle. The effective resistance between any two corners of the triangle is

(a) 9 ohms

(b) 12 ohms

(c) 6 ohms

(d) 8/3 ohms