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ARAB REPUBLIC OF EGYPT
Ministry of Education
General Secondary Education Certificate Examination
(New System)
) ‫االنجليزية‬
‫الفيزياء ( باللغة‬
Physics
) ‫(األسئلة فى أربع صفحات‬
Time: 3 Hours
‫ يسلم الطالب ورقة امتحانيه باللغة العربية مع الورقة المترجمة‬- 1 : ‫تنبيه هام‬
.‫ اإلجابات المتكررة عن أسئلة االختيار من متعدد لن تقدر ويتم تقدير اإلجابة األولى فقط‬-2
Answer FOUR questions only from the following
Question (1)
A) Write down the scientific term that expresses each of the following statements:
1) The number of bonds broken per second will be equal to the number of bonds mended per
second in a semiconductor crystal.
2) The scale deflection per unit current intensity passing through the galvanometer coil.
3) The value of the direct current that generates the same rate of thermal effect in a resistor (or the
same power) as that generated by alternating current (AC).
4) A concentrated packet of energy which has linear momentum.
5) The state in which the number of excited atoms exceeds the number of atoms in the lower states
in a lasing medium.
B) First: The opposite diagram shows graphical relations of some variables, what is the label
of graphical line that represents each relation of
the following?
1) Between the current intensity and the current frequency
in a non-inductive ohmic resistance connected to AC
dynamo.
2) Between the wavelength having maximum intensity
emitted by a hot body and its temperature on Kelvin
scale.
3) Between the electric conductivity of a conductor and
length of that conductor at constant temperature.
Second: Two identical loops, of copper and aluminum are
in a uniform magnetic field perpendicular to their planes
(resistivity of copper is less than that of aluminum). If they are removed from the field rapidly
within the same time interval.
1) The induced emf generated in the copper loop is …
(greater than – less than – equal to)
the induced emf generated in the aluminum loop.
2) In which loop the induced current will be greater? Why?
3) Name the rule used to determine the direction of the induced
current in each loop.
C) Calculate the intensity of currents I1, I2, and I3 shown in the
opposite electric circuit by using Kirchhoff's laws.
1
Question (2)
A) What happens in each of the following cases?
1) If the separation between each two turns of a solenoid is decreased to its half value.
(with respect to the magnetic flux density at a point on its axis inside it)
2) If the capacitance of a capacitor in an AC circuit is increased to its double.
(with respect to its capacitive reactance).
3) If the intensity of incident light on a metal surface (whose frequency is greater than the critical
frequency) in an evacuated tube is increased to double. (with respect
to the maximum kinetic energy of emitted electrons from the metal).
4) If the poles of the battery are reversed in the shown figure.
(with respect to the illumination of the lamp).
5) If the potential difference between the filament and the target in
Coolidge tube is increased,
(with respect to the wavelength of characteristic radiation).
B) First: State ONE application only for each of the following:
1) Laser in military field.
2) Eddy currents.
3) The resonant (tuned) circuit.
Second: Give reason for each of the following:
1) The hot wire ammeter used to measure Both AC and DC currents.
2) The electric conductivity of a semiconductor increases when some impurity atoms are addad to
a pure silicon crystal
3) Step up transformers are used at power stations.
C) A uniform insulated metallic wire of cross sectional area 4.25×10-7 m2 is wound tightly as
10
perfectly adjacent turns of one layer around an iron cylinder of diameter cm to form a
π
solenoid. The solenoid then is connected to a battery of EMF (VB = 10 V) and negligible internal
resistance. The current passing through the solenoid is 5A.
(The resistivity of wire material is 1.7 ×10-8 Ω.m. and the magnetic permeability of
iron is 0.002 Wb/A.m.) (π = 22/7) Calculate
a) Number of turns of the solenoid.
b) The magnetic flux density at a point along the axis of solenoid.
Question (3)
Choose the correct answer from those between brackets for each of the following:
1) A 1mH inductor and 10 F capacitor connected in series to an AC source possess equal
reactance. The angular velocity of this AC source is………
(104 - 100 - 10 - 200)
2) Concerning hydrogen spectrum, the ratio of the longest wavelength in Lyman's series to the
longest wavelength in the Balmer's series is…….
3
4
1
5
) (
2
9
93
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3) If the internal resistance of the battery is negligible in the shown
electric circuit and an ammeter (A) reads 2 A when the switch is
open. The reading on the ammeter (A1) when the switch is closed
will be………….ampere
)0.5 –1 – 2 – 4(
2
4) Two straight parallel wires (A and B) carry electric currents 2A and 8 A. If the force acting on
the wire (A) is F, so the force acting on the wire (B) is……
F
( - F - 2F - 4F)
4
5) A transformer has an input DC voltage of 110 volts, a primary coil of 100 turns and a secondary
coil of 10 turns. What is its output voltage? (55V – 110 V – 220 V – zero)
B) First: Mention the scientific idea on which each of the following depends.
1) Connecting the electric appliances at home in parallel.
2) Studying the crystalline structure of solids using x-rays.
3) Measuring resistance by the ohmmeter.
Second: When does each of the following values equal zero?
1) The magnetic force acting on straight wire carrying an electric current placed in a uniform
magnetic field.
2) The rate of change of magnetic flux in linkage with a coil rotating in a uniform magnetic field.
3) The output of optionality gate. (OR logic gate).
C) In the opposite diagram, a series AC circuit contains a
coil, a capacitor and a resistor. If the effective voltage
across each of the coil, the capacitor and the resistor is
50 V, and a current of effective value 2 A passes
through the circuit, calculate each of the following
when the switch (s) is closed
1) The circuit impedance.
2) The maximum value of voltage across the
capacitor.
3) The power consumed as heat energy in the circuit.
Question (4)
A) What do we mean by saying?
1) The current gain of a transistor =100
2) The self-induction coefficient of a coil = 0.01 H
3) The magnetic dipole moment = 200A.m2
4) The specific resistance of a conductor = 1.68×10-8 Ω.m
5) The work function of a metal = 1.9 eV
B) First: Mention two factors only that affect each of the following:
1) The magnetic flux density at the center of a circular coil carrying an electric current.
2) The coefficient of mutual induction between two coils.
3) The total current passing through a closed
electric circuit.
Second: The opposite figure shows the energy
level diagram for He - Ne laser.
1) How is the helium atom transmitted to its
energy level E3?
2) Why is energy transferred from a helium
atom to a neon atom?
3) Why do neon atoms accumulate in the
excited level E2?
3
C) A small generator coil is rotated at a rate 60 revolutions per minute in the uniform magnetic
field. An emf is generated in the coil when its plane is parallel to the magnetic field is 0.4 Volt.
Calculate:
1) The average value induced emf through ¼ revolution.
2) The maximum value of the emf generated in the generator coil if the rate of rotation is increased
to 90 revolutions per minute
3) The instantaneous emf generated in the generator coil after 3 seconds from being parallel to the
direction of magnetic field.
Question (4)
A) 1- Mention the necessary condition to obtain each of the following:
1) A 3D image.
2) A unidirectional current from alternating current generator.
3) Measuring high potential differences by the galvanometer
2- The opposite figure repersents a npn transistor in a common
emitter mode.
1) Why has the base (P) got a small width?
2) What happens to the output voltage (Vout) if the current base (IB)
increases?
B) First: What is the role played by each of the following?
1) The pair of spiral springs in the galvanometer.
2) The objective lens of the telescope of the spectrometer.
3) Two mirrors in laser generation devices.
Second: How can you (without drawing) achieve each of the following?
1) Converting the moving coil galvanometer into an ammeter.
2) Increasing the power acting of the electric motor.
3) Obtaining P- type crystal.
C) In The AC circuit consists of inductive coil connected in series, it is found that the inductive
reactance XL changes with the angular velocity (ω) according to the following table:
400 800 1000 2000 3200 4000
ω (rad/sec)
16
32
40
80
128
160
XL (Ω)
Plot a graphical representation of the relation between the capacitive reactance (XL) on Y –axis and
the angular velocity (ω) on X –axis. From the graph, find:
a) The value of inductive reactance at 1600 rad/sec.
b) The self-inductance of the coil.
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