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ISC Class 12 Physics Solved Question Paper 2005

Short Answer Type

41.

Why are neutrons considered as ideal particles for nuclear fission reactions ? Calculate the energy released in the following nuclear reaction.

₁H²+ ₁H²→₂H⁴ +energy

(mass of 1H² = 2.014102 u, mass of ₂He⁴ = 4.002604 u).

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42. What is LED ? Explain how radiations are given out by LED.

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43. The output of a OR gate is connected to a NOT gate as shown in the figure given below. Name the new gate formed. Draw the logic symbol and truth table of the new gate.

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Long Answer Type

44. Two cells of same e.m.f. E, but different internal resistance r₁ and r₂ are connected to an external resistance R as shown in the figure. The voltmeter V reads zero. Obtain an expression for R in terms of r₁ and r₂. Calculate the voltage across the cell of internal resistance r₂. (Assume that the voltmeter V is of infinite resistance).

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45. In the figure given below, PQ is a long straight wire carrying a current of 5A in the direction of the arrow. An electron travels with a velocity of 10⁶ m/s at a distance 10 cm from the wire in the same direction of the current. Calculate the magnitude and direction of the force experienced by the electron.

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46. Explain with necessary formula (no derivation) how you will compare the magnetic moments of two magnets by equal distance method using a deflection magnetometer in tan A position.

To compare the magnetic moments, tan A position equal distance method will be used.

One of the magnets of the magnetic moment M₁ is placed on one of its arms.

The readings of both the ends of aluminium pointer are noted.

The magnet is reversed end to end in the same position and the readings of both the ends of the pointer are again noted.

The magnet is now taken to the other arm and the readings are taken by keeping the magnet at the same distance d from the centre of the compass box.

The average value of these eight readings is forced out as θ₁.

The experiment is repeated with the second magnet of Moment M₂, keeping the magnet at the distance d from the centre of the compass box.

The average of the eight readings is noted as θ₂.

Let 2l₁ and 2l₂ be the lengths of the two magnets. The magnetic fields produced by the magnets of moments M₁ and M₂ at the centre of the compass box are B₁ and B₂respectively.

If B_H is the horizontal component of the magnetic field at the place then,