The magnetic field inside a long, straight, current-carrying solenoid is:
A. Uniform (same at all points)
B. Directly proportional to the radius of the solenoid
C. Zero
D. Stronger at the ends than at the center
Answer: Option A
Solution (By JKSSB Mock Tests)
An ideal solenoid consists of tightly packed coils. When current passes through it, the magnetic field lines inside the solenoid are parallel straight lines. This indicates that the magnetic field is uniform in magnitude and direction at all points strictly inside the central region of the solenoid. The field strength is given by B = mu_0 * n * I.
Explanation:
RADAR (Radio Detection and Ranging) uses microwaves, a type of radio wave but usually specific microwave band. Often answer is microwaves. But radio waves also correct. I'll specify microwave as typical answer. Could be radio. Better: microwave. Many exams say microwaves. I'll stick with B.
Explanation:
R ∝ L, inversely proportional to A. Longer wire more resistance. Thicker wire less resistance. R = ρL/A. Resistivity ρ constant for material.
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