ISC (Science) ISC Class 12 - CISCE Question Bank Solutions for Physics (Theory)

A point object O is placed at a distance of 15cm from a convex lens L of focal length 1 Ocm as shown in Figure 5 below. On the other side of the lens, a convex mirror M is placed such that its distance from the lens is equal to the focal length of the lens. The final image formed by this combination is observed to coincide with the object O. Find the focal length of the convex mirror

In a gamma ray emission from nucleus : 

Write any one use for each of the following mirrors : 

(a) Convex

(b) Concave 

The half-life of radium is 1550 years. Calculate its disintegration constant (`lambda`) . 

Copy and complete the following table for a radioactive element whose half-life is 10 minutes. Assume that you have 30g of this element at t = 0.

Obtain an expression for electric potential ‘V’ at a point in an end-on position i.e. axial position of the electric dipole. 

Derive the law of reflection using Huygen’s Wave Theory. 

(i) Draw a labelled circuit diagram of a half wave rectifier and give its output waveform.

(ii) Draw a symbol for NOR gate and write its its truth table. 

(i) Draw a neat circuit diagram to study the input and output characteristics of a common emitter transistor.

(ii) Draw the symbol for AND gate and write its truth table.

A radioactive substance decays to 1/16^th of its initial mass in 40 days. The half-life of the substance, in days, is: 

With what type of source of light are cylindrical wave fronts associated?

The total energy of an electron in the ground state of the hydrogen atom is -13·6 eV. Its total energy, when a hydrogen atom is in the first excited state, is ______.

Name the physical principle on which the working of optical fibers is based.

Write the expression for the Lorentz force F in vector form.

The half-life of a certain radioactive element is 3.465 days. Find its disintegration constant.

A coil has a self-inductance of 0·05 Henry. Find the magnitude of the emf induced in it when the current flowing through it is changing at the rate of 100 As^-1.

PQ is a long straight conductor carrying a current of 3A as shown in Figure below. An electron moves with a velocity of 2 x 10⁷ ms^-1 parallel to it. Find the force acting on the electron.

The figure below shows the positions of a point object O, two lenses, a plane mirror and the final image I which coincides with the object. The focal length of the convex lens is 20 cm. Calculate the focal length of the concave lens.

Answer the following questions with reference to Millikan’s oil drop experiment:
(i) What is an atomiser?
(ii)What is the use of an X-ray tube?
(iii) What is the unique property shown by the charge of an oil drop?

Define Curie temperature.