20.013m
20.009m
20.004m
20.002m
Correct answer is C
The increase in length of the steel rail is given by
= α 10
= 11 x 10-6 x 20 x (40 -20)
= 11 x 10-6 x 20 x 20
= 4.4 x 10-3
∴ Final length will be original length plus increase in length
= 20 + 4.4 x 10-3
= 20 + 0.0044
= 20.0044m
2v/t
v/5t
v/4t
v/2t
Correct answer is C
In vibration in a closed pipe/tube as shown in the figure, fundamental note is produced at the first position of resonance. When the length of the air column L = λ/4; => λ = 4L. Since the open end of the tube is taken as an antinode; and closed end as the node.
Thus the associated frequency is given by
f = V/λ = V/4L
∴ f = V/4L
Thermal equilibrium between two object exist when
the temperature of both objects are equal
the quantity of heat of both objects is the same
the heat capacities of both objects are the same
one object losses heat continuously to the other
Correct answer is A
Two thermal objects are said to be in a thermal equilibrium when the temperature of both objects are equal. Generally, heat flows from an object at a higher temperature to the one at a lower temperature until both temperature are the same, during which the two bodies are said to be in thermal equilibrium
15.0
2.5
1.5
0.4
Correct answer is B
Form the lens formula = 1/U + 1/V = 1/f
=> 1/10 + 1/25 = 1/f;
∴ (5 + 2) / 50 = 1/f
∴ f = 50/7cm
since the image is observed on a screen, it is a real image. Thus magnification
M = f/U-f
| = | __50/7 |
| 10 - 50/7 |
| ∴ M = | 50/7 |
| 20/7 |
= 50/7 x 7/20 = 2.5
0.95m
0.60m
0.50m
0.45m
Correct answer is D
In vibration in a closed pipe/tube, the first resonance occurs at a position L = V/4f,
when reading from the top of the tube,
| L1 = | _340 |
| 4 x 340 |
= 0.25m
L2 = 3V/4f
| L2 = | 3 x 340 |
| 4 x 340 |
= 0.75m
L3 = 5V/4f
| L3 = | 5 x 340 |
| 4 x 340 |
= 1.25m
However, the effective length of the tube is 1.2m. Thus reading from below, the first position of resonance will be 1.20 - 0.75m = 0.45m
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