# KVPY (Kishore Vaigyanik Protsahan Yojana) Stream SB-SX (Class 12 & 1st Year B.Sc.) Physics: Questions 159 - 161 of 268

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## Question number: 159

MCQ▾

### Question

A wire with linear density of is stretched between two rigid supports. Tension on the wire is 540 N. The wire resonates at 450 Hz. The next frequency at which wire resonates is 540 Hz. The length of the wire is –

### Choices

Choice (4) Response

a.

b.

c.

d.

## Question number: 160

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.

### Choices

Choice (4) Response

a.

700 C

b.

1500 C

c.

500 C

d.

1000 C

## Question number: 161

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

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