1
Choose the correct answer for the following :
(5 marks)
1- In an adiabatic process, there is :
A no energy transfer.
B
no work done.
C no temperature change.
D no volume change.
2-Polarization occurs by reflection if the Brewster angle  achieves the condition:
A tan=n1/n2
B sin  =mλ/d
C tan=n2/n1
D sin  = d/mλ
3-The equivalent resistance of the four resistors shown in the figure is
A 0.2 Ω
B 5Ω
C 10 Ω
D 20 Ω
4- The energy required to convert 1 g of water to steam at 100 oC is: (Lv= 2.26 x 106 J/kg)
A
3300 J
B
2.26 x 108 J
C 2.26 J
D 2260 J
5- Total internal reflection occurs when light travels from a medium of index of refraction n1 to
another of index of refraction n2 , where:
A n1=n2
B
n1  n2
C
n1  n2
D n1 =1
2
A sinusoidal wave traveling in the positive x direction has an
amplitude of 15 cm, a wavelength of 40 cm, and a frequency of 8 Hz.
The vertical position of an element of the medium at t = 0 and x = 0 is
also 15 cm, as shown in the figure:
(A) Find the wave number k, period T, angular frequency , and
speed v of the wave.
(B) Determine the phase constant , and write a general expression
for the wave function.
(5 marks)
3
A train is moving parallel to a highway with a constant speed of 20 m/s. A car is traveling in the
same direction as the train with a speed of 40 m/s. The train whistle sounds at a frequency of 320
Hz. When the car is behind the train, what frequency does an occupant of the car observe for the
train whistle? (The speed of sound in air v = 343 m/s)
(5 marks)
4
Two slabs of thickness L1 and L2 and thermal conductivities k1 and k2
are in thermal contact with each other as shown in the figure. The
temperatures of their outer surfaces are Tc and Th , respectively, and
Th . T c.
Prove that the rate of energy transfer through the two slabs is given by:
𝑷=
𝑨(𝑻𝒉 − 𝑻𝒄 )
(𝑳𝟏 ⁄𝒌𝟏 ) + (𝑳𝟐 ⁄𝒌𝟐 )
5
A sample of an ideal gas is in a vertical cylinder fitted
with a piston. As 5.79 kJ of energy is transferred to the
gas by heat to raise its temperature, the weight on the
piston is adjusted so that the state of the gas changes
from point A to point B along the semicircle shown in
the figure. Find the change in internal energy of the
gas.
(5 marks)
6
White light is spread out into its spectral components by a diffraction grating. If the grating
has 2000 grooves per centimeter, at what angle does red light of wavelength 640 nm appear in
first order?
(5 marks)
7
A resistor is constructed of a carbon rod that has a uniform cross-sectional area of 5 mm2.
When a potential difference of 15 V is applied across the ends of the rod, the rod carries a
current of 4 x 10-3 A. Find (a) the resistance of the rod and (b) the rod’s length. (the resistivity
of carbon is  = 3.5x10-5 .m)
(5 marks)
8
Find I1, I2, and  in the circuit shown.
I3 = 2 A
With Best Wishes ,,,
Dr. Ahmed Ismail