When a DC voltage is applied at the two ends of a circuit kept in closed box, it is observed that the current gradually increases from zero to a certain value and then remains constant. What do you think that the circuit contains?

• A

  A resistor alone
• B

  A capacitor alone
• Correct answer
  C

  A resistor and an inductor in series
• D

  A resistor and a capacitor in series

Solution

Hint: LR circuit transient

Hence, the correct answer is option: 'C'.