Science (English Medium) Class 12 - CBSE Question Bank Solutions

A heavy nucleus X of mass number 240 and binding energy per nucleon 7.6 MeV is split into two fragments Y and Z of mass numbers 110 and 130. The binding energy of nucleons in Y and Z is 8.5 MeV per nucleon. Calculate the energy Q released per fission in MeV.

The wavefronts of a light wave travelling in vacuum are given by x + y + z = c. The angle made by the direction of propagation of light with the X-axis is _________ .

The wavefronts of light coming from a distant source of unknown shape are nearly _________ .

Calculate the electric field in a copper wire of cross-sectional area 2.0 mm² carrying a current of 1 A.
The resistivity of copper = 1.7 × 10^–8 Ω m

A wire has a length of 2.0 m and a resistance of 5.0 Ω. Find the electric field existing inside the wire if it carries a current of 10 A.

Consider the situation shown in figure (31-E29). The width of each plate is b. The capacitor plates are rigidly clamped in the laboratory and connected to a battery of emf ε. All surfaces are frictionless. Calculate the value of M for which the dielectric slab will stay in equilibrium.

The susceptibility of magnesium at 300 K is 1.2 × 10⁻⁵. At what temperature will the susceptibility increase to 1.8 × 10⁻⁵?

A metallic loop is placed in a nonuniform magnetic field. Will an emf be induced in the loop?

An inductor is connected to a battery through a switch. Explain why the emf induced in the inductor is much larger when the switch is opened as compared to the emf induced when the switch is closed.

Figure shows a horizontal solenoid connected to a battery and a switch. A copper ring is placed on a frictionless track, the axis of the ring being along the axis of the solenoid. As the switch is closed, the ring will __________ .

Suppose we have 12 protons and 12 neutrons. We can assemble them to form either a ²⁴Mg nucleus or two ¹²C nuclei. In which of the two cases more energy will be liberated?

The mass number of a nucleus is equal to

As the mass number A increases, the binding energy per nucleon in a nucleus

Which of the following is a wrong description of binding energy of a nucleus?

In one average-life,

The speed of light in glass is 2.0 × 10⁸ m s⁻¹. Does it violate the second postulate of special relativity?

For nuclei with A > 100,
(a) the binding energy of the nucleus decreases on an average as A increases
(b) the binding energy per nucleon decreases on an average as A increases
(c) if the nucleus breaks into two roughly equal parts, energy is released
(d) if two nuclei fuse to form a bigger nucleus, energy is released.

Assume that the mass of a nucleus is approximately given by M = Am_p where A is the mass number. Estimate the density of matter in kgm⁻³ inside a nucleus. What is the specific gravity of nuclear matter?

A neutron star has a density equal to that of the nuclear matter. Assuming the star to be spherical, find the radius of a neutron star whose mass is 4.0 × 10³⁰ kg (twice the mass of the sun).