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Electrical Formula MCQs cover all important formulas such as Charge, Capacitance, Inductance, Resistance, Power, and others. Among the list of formulas, the most commonly used electrical formulas are related to voltage, current, power, and resistance. Here is a list of Important Electrical Formulas covered in the article:
Electrical Formulas
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Current Electricity Detailed Video Explanation:
Ques 1: The rate at which an electric type charge is converted from electrical energy to mechanical or other forms of energy then it is represented as____
- Electric power
- Mechanical power
- Chemical energy
- Magnetic energy
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Answer: The correct answer is a. Electrical Power
Explanation: The rate at which an electric type charge is converted from electrical energy to mechanical or other forms of energy then it is represented as electrical power.
Ques 2: The relation between Power, Resistance, and Current is____
- P=I2/R
- P=I2R
- P=VI2
- None of the above
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Answer: The correct answer is b. P=I2R
Explanation: In P = I2 R, Power is directly proportional to Resistance ( Current Constant throughout the circuit ).
Ques 3: Under no-load conditions, the transmission line carrying a current because of
- Heating effect
- Capacitance effect
- Chemical effect
- Transmission effect
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Answer: The correct answer is b. Capacitance effect
Explanation: Under no-load conditions, the transmission line carries a current because of the capacitance effect. Under the no-load condition, the current in the line is due to the flow of charge only (Increase Ferranti effect), and the charging current is due to the formation of capacitance between the transmission line and the earth.
Ques 4: The opposing capacity of materials against the current flow is:
- Conductance
- Inductance
- Susceptance
- Resistance
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Answer: The correct answer is b. Inductance
Explanation: The opposing capacity of materials against the current flow is resistance.
Ques 5: The phenomenon in which there is an induced current in one coil due to the current in a neighboring coil is?
- Electromagnetism
- Susceptance
- Mutual inductance
- Steady current
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Answer: The correct answer is c. Mutual Inductance
Explanation: When there is a current in a coil, due to the magnetic field caused by the current there is currently induced in the neighboring coil as well. This is known as mutual inductance.
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Ques 6: What is the SI unit of mutual inductance?
- Ohm
- Henry
- Volt
- Siemens
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Answer: The correct answer is b. Henry
Explanation: Mutual inductance is the inductance between the two neighboring coils. Since it is a type of inductance, its unit is that of inductance, that is, henry.
Ques 7: The alternating current voltage have _______________
- Phase
- Neutral
- Both a and b
- None of the above
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Answer: The correct answer is c. Both a and b
Explanation: The alternating current voltage has both phase and neutral. The three pins correspond to earth, neutral, and phase. The phase line is the one that carries current, the neutral line provides the return path to balance the flow of current, and finally earthing is purely used for safety purposes.
Ques 8: In which one of the following voltage the polarity is fixed?
- AC voltage
- DC voltage
- Both a and b
- None of the above
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Answer: The correct answer is b. DC Voltage
Explanation: In DC voltage the polarity is fixed whereas in AC voltage the polarity is not fixed
Ques 9: In the series combination of two or more than two resistances
- the current through each resistance is the same.
- the voltage through each resistance is the same.
- neither current nor voltage through each resistance is the same.
- both current and voltage through each resistance are the same.
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Answer: The correct answer is a. the current through each resistance is the same.
Explanation: In a series combination current across its circuit components is always and in a parallel combination the voltage across the circuit components is constant.
Ques 10: The speed at which the current travels in a conductor is near:
- 3 × 104 ms-1
- 3 × 106 ms-1
- 3 × 108 ms-1
- 3 × 1010 ms-1
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Answer: The correct answer is d. 3 × 108 ms-1
Explanation: In a conductor, the speed of the electric field is almost equal to c=3×108m/s. Hence, this is the speed with which electric current travels in a conductor.
Though the drift speed is of the order of 10−3m/s and the speed of electrons is of the order of 106m/s. The current starts flowing as soon as the electron starts drifting and hence the speed of the current is the same as that of the electric field is nearly 3×108m/s.
Ques 11: A cell of e.m.f. ‘E’ and internal resistance r is connected in series with an external resistance nr. Then the ratio of the terminal potential difference to e.m.f. is
- \(\frac{1}{n}\)
- \(\frac{1}{n+1}\)
- \(\frac{n}{n+1}\)
- \(\frac{n+1}{n}\)
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Answer: The correct answer is c. \(\frac{n}{n+1}\)
Explanation: \(i= \frac{E}{r+nr}= \frac{E}{(n+1)r}\)
Terminal difference of cell = \(V = E -ir=E- \frac{Er}{nr+r}\)
⟹\(V=\frac{Enr}{nr+r} = \frac{n}{n+1}\)
The ratio of V and E is \(\frac{n}{n+1}\)
Ques 12: The temperature coefficient of resistance of a wire is 0.00125 per degree Celcius. At 300K its resistance is 1 ohm. The resistance of the wire will be 2 ohms at the following temperature:
- 1100 K
- 854 K
- 1127 K
- 1154 K
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Answer: The correct answer is a. 1100K
Explanation: Step 1: Applying Relation between Temperature and Resistance: R=R0(1+α(T2−T1))
Given Initial resistance at 300K is 1Ω.
Let temperature be T when final resistance becomes 2Ω
⇒ 2Ω=1Ω(1+0.00125(T−300K))
⇒ 1=5/4×10−3(T−300K)
∴ T=1100K
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