Discussion
In the circuit shown in the figure, the power dissipated in 30 Ω resistor will be maximum, if the value of R is :
Answer: D
The power in the 30 Ω resistor is maximum when R is zero.
The 30 Ω resistor is fixed, so its power \(P = I^{2} \times 30\) depends only on the current through it. That current is
\[ I = \frac{V}{30 + (R \parallel 16)} \]
which is largest when the parallel combination R ∥ 16 is smallest. With R = 0 the variable resistor shorts the 16 Ω resistor, the parallel combination becomes 0, and I = V/30, the maximum possible.
The maximum power transfer idea, matching R to the load, does not apply here: it maximises power for a fixed source resistance feeding a variable load, whereas here the load is fixed and R is in the source path.
Post your comment
Please log in or register to post a comment.
Examination Categories
- SSC Exams
- Banking Exams
- Teaching Exams
- Civil Services Exams
- Railways Exams
- Engineering Recruitment Exams
- Defence Exams
- State Government Exams
- Police Exams
- Insurance Exams
- Nursing Exams
- Other Government Exams
- NRA CET
- PG Entrance Exams
- Campus Placement
- MBA Entrance Exams
- CUET and UG Entrance
- Judiciary Exams
- Regulatory Body Exams
- Software Development