Which of the following uses the principle of electromagnetic induction?
A. Incandescent bulb
B. Electric heater
C. Fuse
D. Transformer
Answer: Option D
Solution (By JKSSB Mock Tests)
Transformer, induction cooker, generator use induction. Heater and bulb use heating effect of current. Fuse melts by heat. Induction: changing magnetic field induces current.
Explanation:
A rainbow is formed by sunlight interacting with water droplets. As light enters the droplet, it undergoes refraction and dispersion (separating into colors). The light then strikes the back of the droplet and undergoes total internal reflection. Finally, it undergoes a second refraction as it exits, spreading the spectrum out for the observer to see.
Explanation:
Resistance R = V²/P = 220²/100 = 484 Ω. At 110 V, P = V²/R = 110²/484 = 12100/484 = 25 W. Assuming resistance constant. Power reduces to quarter when voltage halved (P ∝ V² for fixed R).
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