Chapter 34
Electromagnetic Waves
Electromagnetic Waves
Mechanical waves require the presence of a medium.
Electromagnetic waves can propagate through empty space.
Maxwells equations form the theoretical basis of all electromagnetic waves that
propagate th
Question 15.1:
A string of mass 2.50 kg is under a tension of 200 N. The length of the stretched string is
20.0 m. If the transverse jerk is struck at one end of the string, how long does the
disturbance take to reach the other end?
Answer
Mass of the str
Question 14.1:
Which of the following examples represent periodic motion?
A swimmer completing one (return) trip from one bank of a river to the other and back.
A freely suspended bar magnet displaced from its N-S direction and released.
NS
A hydrogen mol
Question 13.1:
Estimate the fraction of molecular volume to the actual volume occupied by oxygen gas
at STP. Take the diameter of an oxygen molecule to be 3.
Answer
Diameter of an oxygen molecule, d = 3
Radius, r
= 1.5 = 1.5 108 cm
Actual volume occupied
Question 12.1:
A geyser heats water flowing at the rate of 3.0 litres per minute from 27 C to 77 C. If
the geyser operates on a gas burner, what is the rate of consumption of the fuel if its heat
of combustion is 4.0 104 J/g?
Answer
Water is flowing at a
Question 11.1:
The triple points of neon and carbon dioxide are 24.57 K and 216.55 K respectively.
Express these temperatures on the Celsius and Fahrenheit scales.
Answer
Kelvin and Celsius scales are related as:
TC = TK 273.15 (i)
Celsius and Fahrenheit
Question 10.1:
Explain why
The blood pressure in humans is greater at the feet than at the brain
Atmospheric pressure at a height of about 6 km decreases to nearly half of its value at the
sea level, though the height of the atmosphere is more than 100 km
Question 9.1:
A steel wire of length 4.7 m and cross-sectional area 3.0 105 m2 stretches by the same
amount as a copper wire of length 3.5 m and cross-sectional area of 4.0 105 m2 under a
given load. What is the ratio of the Youngs modulus of steel to tha
Question 8.1:
Answer the following:
You can shield a charge from electrical forces by putting it inside a hollow conductor.
Can you shield a body from the gravitational influence of nearby matter by putting it
inside a hollow sphere or by some other means
Question 7.1:
Give the location of the centre of mass of a (i) sphere, (ii) cylinder, (iii) ring, and (iv)
cube, each of uniform mass density. Does the centre of mass of a body necessarily lie
inside the body?
Answer
Geometric centre; No
The centre of mas
Question 6.1:
The sign of work done by a force on a body is important to understand. State carefully if
the following quantities are positive or negative:
work done by a man in lifting a bucket out of a well by means of a rope tied to the bucket.
work don
Question 5.1:
Give the magnitude and direction of the net force acting on
a drop of rain falling down with a constant speed,
a cork of mass 10 g floating on water,
a kite skilfully held stationary in the sky,
a car moving with a constant velocity of 30 km
Question 4.1:
State, for each of the following physical quantities, if it is a scalar or a vector:
volume, mass, speed, acceleration, density, number of moles, velocity, angular frequency,
displacement, angular velocity.
Answer
Scalar: Volume, mass, speed
Question 3.1:
In which of the following examples of motion, can the body be considered approximately
a point object:
a railway carriage moving without jerks between two stations.
a monkey sitting on top of a man cycling smoothly on a circular track.
a spi
Units And Measurements (Physics)
Question 2.1:
Fill in the blanks
The volume of a cube of side 1 cm is equal to.m3
The surface area of a solid cylinder of radius 2.0 cm and height 10.0 cm is equal to .
(mm)2
A vehicle moving with a speed of 18 km h1covers
MCQs of Plasma Physics
by Prof. V.K. Tripathi , IIT Delhi, New Delhi.
Lecture 1
Problem 1: Consider a singly ionized sphere of electron density no, radius R and electron
temperature T. Due to thermal motions electrons of the layer of width near the surfac
SAMPLE QUESTIONS
AP Physics 1 and
AP Physics 2 Exams
Originally published in the October 2012
AP Physics 1: Algebra-Based and
AP Physics 2: Algebra-Based Curriculum Framework
The College Board
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This book is provided FREE with
test registration by the
Graduate Record Examinations Board.
Graduate Record Examinations
This practice book
contains
one actual full-length
GRE Physics Test
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Become familiar with
test structure and
TExES
| Texas Examinations of Educator Standards
Preparation
Manual
143 Physics/Mathematics 812
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Solution
Week 29
(3/31/03)
Balls in a semicircle
(a) Let M/N be the mass of each ball in the semicircle. We need the deection
angle in each collision to be = /N . However, if the ratio /m is too small,
then this angle of deection is not possible.
From Pro
Solution
Week 28
(3/24/03)
Rectangle in a circle
In the gure below, let the incenters of triangles ADB and ADC be X and Y ,
respectively.
B
C
X
A
Y
P
D
Angle XAY can be written as
XAY
=
XAD Y AD
1
1
=
BAD
CAD
2
2
1
=
BAC
2
1
=
(BC ).
4
A similar argument
Solution
Week 27
(3/17/03)
Relativistic cookies
Let the diameter of the cookie cutter be L, and consider the two following reasonings.
In the lab frame, the dough is length-contracted, so the diameter L corresponds
to a distance larger than L (namely L)
Solution
Week 26
(3/10/03)
Drunken walk
(a) First Solution: Imagine a large number of copies of the given setup proceeding simultaneously. After each drunk takes his rst step in all of the copies,
the average position of all of them remains the same (name
Solution
Week 25 (3/3/03)
Maximum deection angle
First Solution: Although it is possible to solve this problem by working in the lab
frame (see the second solution below), it is much easier to make use of the centerof-mass frame. Let M have initial speed
Solution
Week 24
(2/24/03)
Verifying weights
(a) Each weight may be used in three dierent ways. It may be put on the left
side, the right side, or not used at all. Therefore, if we have n weights, they
may be combined in 3n ways. This is true because in a
Solution
Week 23
(2/17/03)
V (x) versus a hill
Quick solution: Consider the normal force, N , acting on the bead at a given
point. Let be the angle that the tangent to V (x) makes with the horizontal, as
shown.
N
V(x)
mg
The horizontal F = ma equation is
Solution
Week 22
(2/10/03)
Trading envelopes
(a) Let your envelope contain N dollars. Then the other envelope contains either
2N or N/2 dollars. If you switch, the expected value of your assets is 1 (2N ) +
2
1
(N/2) = 5N/4. This is greater than N . There
Solution
Week 21 (2/3/03)
Ball on turntable
Let the angular velocity of the turntable be , and let the angular velocity of
z
the ball be . If the ball is at position r (with respect to the lab frame), then its
velocity (with respect to the lab frame) may
Solution
Week 18
(2/13/03)
Distribution of primes
A necessary and sucient condition for N to be prime is that N have no prime
factors less than or equal to N . Therefore, under the assumption that a prime p
divides N with probability 1/p, the probability
Solution
Week 16
(12/30/02)
Letters in envelopes
First Solution: (This solution is due to Aravi Samuel.) We will use induction on
N . Let BN denote the number of bad congurations where none of the N letters
end up in the correct envelope. We claim that BN