Physics 2006 Jamb Examination
Physics 2006 Jamb Examination
Question 11
The main purpose of the transformer in an a.c radio set is to?
In a.c. radio sets, the transformer is mainly used to step down the high mains voltage to a safer lower voltage for the circuit.
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Question 12
An electric heater with a p.d of 240 V connected across its terminals has a total resistance of 960Ω. find the power rating of the heater.
Power \( P = \dfrac{V^2}{R} = \dfrac{240^2}{960} = \dfrac{57600}{960} = 60 \; W \).
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Question 13
If the capacitance of a capacitor is \( C = \dfrac{\varepsilon A}{d} \)
which of the following parameters is varied when a variable capacitors is used for tuning radio sets?
which of the following parameters is varied when a variable capacitors is used for tuning radio sets?
In variable capacitors used in radios, capacitance is adjusted by varying the effective plate area (A) and separation (d).
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Question 14
When an a.c. voltage is applied to a capacitor, no power is consumed because the current
In a pure capacitor, current leads the voltage by 90°, so average power consumed is zero.
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Question 15
The electrolyte in the Nickei-iron (Nife) accumulator is
The electrolyte used in a Nickel-Iron (NiFe) accumulator is potassium hydroxide solution.
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Question 16
During electrolysis, 2.0 g of a metal is deposited using a current of 0.5 A in 3 hours. The mass of the same metal which can be deposited using a current of 1.5 A in 1 hour is?
Mass deposited \( m \propto I \times t \).
For first case: \( m_1 = 2.0 \; g, I_1t_1 = 0.5 \times 3 = 1.5 \; Ah \).
For second case: \( I_2t_2 = 1.5 \times 1 = 1.5 \; Ah \).
Since \( I_1t_1 = I_2t_2 \), \( m_2 = m_1 = 2.0 g \).
For first case: \( m_1 = 2.0 \; g, I_1t_1 = 0.5 \times 3 = 1.5 \; Ah \).
For second case: \( I_2t_2 = 1.5 \times 1 = 1.5 \; Ah \).
Since \( I_1t_1 = I_2t_2 \), \( m_2 = m_1 = 2.0 g \).
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Question 17
When a certain a.c supply is connected to a lamp, it lights with the same brightness as it does with a 12 V d.c battery. Then r.m.s value of the a.c supply is?
Brightness depends on power, which is proportional to the rms value of voltage. Since brightness is the same, the rms value of the a.c is 12 V.
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Question 18
An ammeter of resistance 5Ω has a full-scale deflection when a current of 50 mA flows in it. The value of the resistor required to adapt it to measure a current of 5 A is?
Voltage across meter = \( IR = 0.05 \times 5 = 0.25 V \).
For 5 A, shunt must carry 4.95 A with same 0.25 V drop.
Shunt resistance = \( \dfrac{0.25}{4.95} \approx 0.05 \; \Omega \).
For 5 A, shunt must carry 4.95 A with same 0.25 V drop.
Shunt resistance = \( \dfrac{0.25}{4.95} \approx 0.05 \; \Omega \).
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Question 19
The motion of smoke particles from a chimney is typical of?
Smoke particles show irregular, zigzag motion caused by collisions with air molecules, a typical random motion.
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Question 20
In an experiment to determine terminal velocity, as the pressure increases, the viscosity off a liquid
Generally, the viscosity of liquids tends to increase with pressure, as the increased pressure can lead to a greater interaction between molecules
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