**RC and L/R Time Constant – Definition**

In the case of **RC time constant**, we will define that a fixed or constant time period a capacitor takes to charge 63.2 percent **voltage**. But the complete charging upto 100% will be complete after 5 time constant. In the case of **L/R time constant,** we can simply understand that an inductor takes 1 L/R time constant to complete the current change upto 63.2%. The only difference between **RC v.s R/L** time constant is just a concept of current and voltage.

**Read More: MCQs of Basic Electronics Questions Test with Answer Key PDF**

The aim to provide **MCQs on RC time constant** in electronic circuit objective questions and answers to understand the formula and calculation of time constant. If you are willing to learn the concepts of** Basic Electronics** MCQs multiple choice questions with answer then read all the multiple choice questions and answers completely. You will be surely qualify for all kinds of **Quiz / tests / Interviews** after understanding the principle of **RC and R/L Time Constant**. If you are a **students, technician or teacher** then you can learn the basic concept of **time constant in electronic circuit **principle, function and applications.

**RC Time Constant in Electronic Circuit (****Objective Questions****)**

**Q1. The time constant is the time required to change upto ________ percent voltage through capacitor and current through inductor. .**

- 62.3
- 63.2
- 64.3
- 63.4

**Answer: b**

**Q2. The transient response is measured in the term of L/R ratio. True / False**

**Answer: True**

**Q3. The formula used to calculate the time constant in inductive circuit is ___________.**

- RC
- L/R
- R/C
- LC/R

**Answer: b**

**Q4. When an inductive Cct is opened, the time constant for current becomes very short**. **True / False**

**Answer: True**

**Q5. The energy stored in the magnetic field is______________________. **

**E**= 64 × 10^{-4 }J**E**= 1/2 LCR**E**= 1/2 LI^{2}- a & c are correct

**Answer: d**

**Q6. When the voltage across the capacitor and current across the inductor becomes equal to the source current or voltage is five time constant . True / False**

**Answer: True**

**Q7. The current in inductor reached to the 63.2% within 0.1 sec then the current rises to 100% within _________ sec.**

- 0.2
- 0.3
- 0.4
- 0.5

**Answer: d**

**Q8. In the inductive circuit, the current reaches to the 63.2% in 1 L/R time constant and becomes 100% within 5 L/R time constant****. ****True / False**

**Answer: True**

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**Q9. The RC time constant becomes __________ with larger value of R & C.**

- shorter
- longer
- a & b are correct
- all are correct

**Answer: b
**

**Q10. The high value of self induced voltage across inductor produces when RL circuit is opened. True / False**

**Answer: True**

**Q11. When RL circuit is opened, the produce self-induce voltage which is ________ than the applied voltage.**

- short
- greater
- infinity
- same

**Answer: b
**

**Q12. The neon bulb requires 90 voltages for the ionization function. True / False**

**Answer: True**

**Q13. The formula to calculate the time constant in capacitive circuit is _____________.**

- RC
- RC/L
- R/C
- R/L × C

**Answer: a
**

**Q14. The energy stored in a capacitor formula is E** = 1/2 CV^{2 }**True / False**

**Answer: True**

**Q15. ****The long or short time constant RC time constant depends on the ____________ of applied voltage.**

- current
- frequency
- pulse width
- voltage

**Answer: c
**

**Q16. A short RC time constant is equal to the one-fifth pulse width of the applied voltage. True / False**

**Answer: True**

**Q17. A ________ RC time constant is equal to the 5 times longer pulse width of applied voltage.**

- Long
- Short

**Answer: b
**

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**Q18. The voltage across R in a RC circuit is called differentiated output. True / False**

**Answer: True**

**Q19. The voltage across C in an RC circuit is called ______________ circuit.**

- integrated
- differentiated

**Answer: a
**

**Q20. A short & medium time constant is generally used for differentiated circuit. True / False**

**Answer: False (Only Short)**

**Q21. A _____________ time constant is generally used for integrated circuit.**

- long
- short
- medium
- b & c are correct

**Answer: d
**

**Q22. Generally, the time constant is made much shorter or longer than a factor of 5 to get better wave shapes. True / False**

**Answer: True**

**Q23. The factor of 0.5 time constant is equal to the amplitude of ______________.**

- 20%
- 50%
- 63%
- 40%

**Answer: d
**

**Q24. The factor of 4-time constant is equal to the amplitude of 98%. True / False**

**Answer: True**

**Q25. The amplitude of 86% is equal to the time constant of _____________.**

- 3
- 4
- 5
- 2

**Answer: d
**

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**Q26. The method of time constant is used for L & C to analysis the non-sinusoidal wave-forms. True / False**

**Answer: True**

**Q27. The ___________ method is used with L & C to analysis the sinusoidal waveform.**

- Reactance
- Inductance
- Time Constant
- All are correct

**Answer: c**