Question 1
Question
Consider the alternating current (Fig. 3). What fraction of its period (T) does it take to reach from zero to half of its amplitude?(hint: sin300=1/2)
Question 2
Question
What particles are the electric current carriers (charge carriers) in metals?
Answer
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Electrons
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Ions
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Electrons and holes
Question 3
Question
For the photoelectric effect to take place, the wavelength (λ) of the incident light must satisfy the following inequality:
Where: ɸ is the minimum energy needed to remove an electron from metal (work function); h is Plank constant.
Answer
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λ ≥ ɸ/h
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λ ≤ hc/ ɸ
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λ ≥ c/ɸ
Question 4
Question
Electric current is measured in units of amps (A) which represent the following rate of change:
Answer
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Charge per time, Q/t
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Energy per charge, E/Q
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Energy per distance, E/x
Question 5
Question
Alternating current (AC):
Question 6
Question
The Oscilloscope measures and displays the relationship between two variables, input (y-axis) andreference (x-axis). Choose the correct pair:
Answer
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Time (input) vs Voltage (reference)
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Voltage (input) vs Time (reference)
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Current (input) vs Voltage (reference)
Question 7
Question
The current carriers inside vacuum tubes are:
Answer
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Electrons
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Ions
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Electrons and holes
Question 8
Question
The term ”charge carrier” refers to
Answer
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Strictly to electrons and holes
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Strictly to electrons and protons
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Any particle that has an electric charge
Question 9
Question
The term ”elementary charge“ refers to
Answer
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The charge of the electron
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The charge of any charge carrier
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The charge of any elementary particle
Question 10
Question
If across 25Ohm resistor is applied 50V (DC) how many Amperes is the current that will flow:
Question 11
Question
What happens to the current (DC) in metallic conductor, if the voltage is doubled?
Answer
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It will be halved
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It will double
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It will stay the same
Question 12
Question
Ohm’s Law states that the magnitude of the electric current is proportional to the applied voltage and inversely proportional to the resistance in the conducting material. Choose one:
Question 13
Question
For Ohmic load in a DC circuit, what would be the change in power consumption if the voltage is halved?(hint: in Ohmic circuits the ratio V/I = constant, and power = V·I)
a. It will double
Answer
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It will double
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It will be halved
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It will be quartered
Question 14
Question
What is the resistance in a load if, when 120 V are applied, it draws a current of 20 Amps:
Question 15
Question
Metals are good conductors of electricity because:
Question 16
Question
A 400 Ohm resistor draws 0.05 A direct current. What is the voltage across the resistor