KVPY Stream SB-SX (Class 12 & 1st Year BSC) Physics: Questions 160 - 162 of 250

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Question number: 160

» Thermodynamics » Measurement of Temperature

MCQ▾

Question

A steel rod (L1 = 10 cm, A1 = 0.02 m2 and k1 = 50 J s-1 m-1 K-1) is welded to a silver rod (L2 = 20 cm, A2 = 0.01 m2, k2 = 400 J s-1 m-1 K-1) as shown in figure below. The ends of the composite rod are maintained at 1500 C and 00 C. The rod is covered with an insulating material so that the heat loss from the sides is negligible. Compute the temperature of the steel-silver junction in the steady state.

Two rods of different metals welded

Two Rods of Different Metals Welded

In figure a steel rod is welded to a silver rod is shown. The ends of the composite rod are maintained at 200 (Degree) C and 0 (Degree) C.

Choices

Choice (4) Response

a.

700 C

b.

1500 C

c.

500 C

d.

1000 C

Question number: 161

» Dual Nature of Matter and Radiation » Einstein's Photoelectric Equation

MCQ▾

Question

A stream of photons having energy 5 eV each impinges on a Lithium surface. The work function of Lithium is 2.9 eV. The emerging photo-electrons are slowed down by copper plate placed 3 mm away. If the potential difference between two metal plates is 1 V, the maximum distance the electrons can move away from the Lithium surface before being turned back is –

Choices

Choice (4) Response

a.

6.3 mm

b.

7.8 mm

c.

5.5 mm

d.

7.0 mm

Question number: 162

» Electromagnetic Waves » Electromagnetic Waves & Characteristics

MCQ▾

Question

The intensity of γ-rays from a source (I0) reduces to I09 after passing through 33 mm thick sheet of lead. The thickness of the sheet for obtaining intensity equal to I03 will be –

Choices

Choice (4) Response

a.

11 mm

b.

24 mm

c.

44 mm

d.

9 mm

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