NEET Physics: Questions 1809 - 1812 of 2098

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Question number: 1809

» Communication System » Basic Elements of Communication System

MCQ▾

Question

A laser beam is used for carrying out surgery because it

Choices

Choice (4) Response

a.

Is highly directional

b.

Is highly monochromatic

c.

Can be sharply focused

d.

Is highly coherent

Question number: 1810

» Oscillations and Waves » Standing Waves in Strings and Organ Pipes

MCQ▾

Question

An open organ pipe is in resonance in its 2 nd harmonic with tuning fork of frequency f 1 now; it is closed at one end. If the frequency of the tuning fork is increased slowly from f l then again a resonance is obtained with a frequency f 2. If in this case the pipe vibrates n th harmonics then

Choices

Choice (4) Response

a.

n=3,f2=34f1

b.

n=5,f2=54f1

c.

n=5,f2=34f1

d.

n=3,f2=54f1

Question number: 1811

» Oscillations and Waves » Reflection of Waves

Assertion-Reason▾

Assertion (Ꭺ)

Velocity of particles, while crossing mean position (in stationary waves) varies from maximum at antinodes to zero at nodes.

Reason (Ꭱ)

Amplitude of vibration at antinodes is maximum and at nodes, the amplitude is zero, and all particles between two successive nodes cross the mean position together.

Choices

Choice (4) Response

a.

Ꭺ is true but Ꭱ is false

b.

Both Ꭺ and Ꭱ are false

c.

Ꭺ is false but Ꭱ is true

d.

Both Ꭺ and Ꭱ are true and Ꭱ is the correct explanation of Ꭺ

Question number: 1812

» Oscillations and Waves » Doppler Effect in Sound

MCQ▾

Question

A whistle giving out 461 Hz approaches a stationary observer at a speed of 44 m/s. The frequency heard by the observer in Hz is

Choices

Choice (4) Response

a.

545 Hz

b.

550 Hz

c.

532 Hz

d.

430 Hz

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