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Choose the correct option.
If a TV telecast is to cover a radius of 640 km, what should be the height of the transmitting antenna?
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Answer briefly.
What are EM waves?
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Answer briefly.
How are EM waves produced?
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Answer briefly.
How does the effective power radiated by an antenna vary with wavelength?
Concept: undefined >> undefined
Answer briefly.
Why should broadcasting programs use different frequencies?
Concept: undefined >> undefined
Solve the numerical problem.
In an EM wave, the electric field oscillates sinusoidally at a frequency of 2 × 1010 Hz. What is the wavelength of the wave?
Concept: undefined >> undefined
Solve the numerical problem.
A TV tower has a height of 200 m. How much population is covered by TV transmission if the average population density around the tower is 1000/km2? (Radius of the Earth = 6.4 × 106 m)
Concept: undefined >> undefined
Solve the numerical problem.
Height of a TV tower is 600 m at a given place. Calculate its coverage range if the radius of the Earth is 6400 km. What should be the height to get the double coverage area?
Concept: undefined >> undefined
The length, breadth, and thickness of a rectangular sheet of metal are 4.234 m, 1.005 m, and 2.01 cm respectively. Give the area and volume of the sheet to correct significant figures.
Concept: undefined >> undefined
Describe what is meant by significant figures.
Concept: undefined >> undefined
Solve the numerical example.
A large ball 2 m in radius is made up of a rope of square cross-section with edge length 4 mm. Neglecting the air gaps in the ball, what is the total length of the rope to the nearest order of magnitude?
Concept: undefined >> undefined
Solve the numerical example.
Nuclear radius R has a dependence on the mass number (A) as R =1.3 × 10-16 A1/3 m. For a nucleus of mass number A = 125, obtain the order of magnitude of R expressed in the meter.
Concept: undefined >> undefined
Solve the numerical example.
Write down the number of significant figures in the following: 0.003 m2, 0.1250 gm cm-2, 6.4 x 106 m, 1.6 x 10-19 C, 9.1 x 10-31 kg.
Concept: undefined >> undefined
Solve the numerical example.
The diameter of a sphere is 2.14 cm. Calculate the volume of the sphere to the correct number of significant figures.
Concept: undefined >> undefined
Answer in one sentence.
Define friction.
Concept: undefined >> undefined
Answer in one sentence.
Why force of static friction is known as ‘self-adjusting force’?
Concept: undefined >> undefined
Answer in one sentence.
Name two factors on which the coefficient of friction depends.
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State any four methods to reduce friction.
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Answer in short.
What is rolling friction? How does it arise?
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Answer in short.
Explain how lubricants help in reducing friction.
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