Question

Direction for Assertion - Reason type questions (A) If both Assertion and Reason are true and reason is the correct explanation of assertion. (B) If both Assertion and Reason are true but Reason is not the correct explanation of assertion. (C) If Assertion is true but Reason is false (D) If both assertion and reason are false A : A transistor amplifier circuit in common emitter configuration has low input impedance \(\mathrm{R}\) : Base-emitter junction is forward biased (A) (B) (C) (D)

Short answer

The correct option is (A), as both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

Step-by-step solution

Check the Assertion

The Assertion states that a transistor amplifier circuit in common emitter configuration has low input impedance. In a common emitter configuration, the emitter of the transistor is the common terminal to both input and output terminals. The input impedance for a common emitter configuration is indeed relatively low compared to other configurations like common base or common collector. Hence, the Assertion is true. #Step 2: Determine if the Reason is true or false#

Check the Reason

The Reason states that the base-emitter junction is forward biased in the common emitter configuration. In a transistor amplifier circuit, the base-emitter junction being forward biased means that the base current flows into the base terminal, and the transistor operates in the active mode. This is a necessary condition for the common emitter configuration to function as an amplifier. Hence, the Reason is true. #Step 3: Determine if the Reason is the correct explanation of the Assertion#

Determine the correlation

The input impedance in a common emitter configuration depends on several factors, such as the transistor parameters and external resistors. However, low input impedance is mainly due to the base-emitter junction being forward biased. When the base-emitter junction is forward biased, it allows a significant amount of current to flow into the base terminal, which results in a low input impedance. Therefore, the Reason is indeed the correct explanation for the Assertion. #Step 4: Choose the correct option#

Answer the question

Since both Assertion and Reason are true, and Reason is the correct explanation of Assertion, the correct option is (A).