Vidaara.orgClass 11 · Physics
CodeVID-P11-14-NTW-01
Nature & Types of Waves — Assignment
Name: ____________________
Roll No.: __________
Date: ____________
General Instructions
- All questions are compulsory.
- Section A carries 1 mark each, Section B 2 marks, Section C 3 marks and Section D 5 marks.
- Show all working for Sections B, C and D. Only final answers are given at the end — for full solutions, raise your doubts with your teacher.
Section A — Multiple Choice Questions
5 × 1 = 5 marks
1.
Waves that need a material medium to travel are called:
- A.electromagnetic waves
- B.mechanical waves
- C.matter waves
- D.shock waves
2.
Crests and troughs are features of:
- A.longitudinal waves
- B.transverse waves
- C.sound waves in air
- D.all waves
3.
The SI unit of frequency is:
- A.second
- B.metre
- C.hertz
- D.newton
4.
The wave speed on a string depends on tension as:
- A.$v\propto T$
- B.$v\propto T^2$
- C.$v\propto\sqrt{T}$
- D.$v\propto\frac{1}{T}$
5.
In the wave $y=A\sin(\omega t-kx)$, the quantity $k$ is the:
- A.amplitude
- B.angular frequency
- C.angular wave number
- D.time period
Section B — Short Answer (2 marks)
3 × 2 = 6 marks
6.
Distinguish between transverse and longitudinal waves with one example each.
7.
A wave of frequency 256 Hz travels at 340 m/s. Find its wavelength.
8.
Why can sound not travel through a vacuum?
Section C — Short Answer (3 marks)
2 × 3 = 6 marks
9.
From $y=0.05\sin(400t-4x)$ (SI units), find the amplitude, wavelength and wave speed.
10.
A string of linear mass density $2\times10^{-3}\ \text{kg/m}$ carries a wave at 50 m/s. Find the tension.
Section D — Long Answer (5 marks)
1 × 5 = 5 marks
11.
Define wavelength, frequency, time period and amplitude. Derive the relation $v=f\lambda$ and state the formula for the speed of a transverse wave on a string.
Answer Key
Section A — Multiple Choice Questions
- (B) mechanical waves
- (B) transverse waves
- (C) hertz
- (C) $v\propto\sqrt{T}$
- (C) angular wave number
Section B — Short Answer (2 marks)
- Transverse: particles vibrate perpendicular to propagation, e.g. wave on a string. Longitudinal: particles vibrate parallel to propagation, e.g. sound in air.
- $\lambda=\frac{v}{f}=\frac{340}{256}\approx1.33\ \text{m}$.
- Sound is a mechanical wave; it needs a material medium whose particles can vibrate and pass on the disturbance, which a vacuum lacks.
Section C — Short Answer (3 marks)
- $A=0.05\ \text{m}$; $k=4\Rightarrow\lambda=\frac{2\pi}{4}=1.57\ \text{m}$; $v=\frac{\omega}{k}=\frac{400}{4}=100\ \text{m/s}$.
- $v=\sqrt{\frac{T}{\mu}}\Rightarrow T=\mu v^2=2\times10^{-3}\times50^2=5\ \text{N}$.
Section D — Long Answer (5 marks)
- Wavelength: distance between consecutive identical points. Frequency: oscillations per second ($f=1/T$). Time period: time for one oscillation. Amplitude: maximum displacement. In one period $T$ the wave advances one wavelength $\lambda$, so $v=\frac{\lambda}{T}=f\lambda$. On a string, $v=\sqrt{\frac{T}{\mu}}$.
Generated by Vidaara.org · Assignment VID-P11-14-NTW-01 · vidaara.org