A convex mirror is used as a rear-view mirror because it MCQ with Answer and Explanation

A convex mirror is used as a rear-view mirror because it
A. Gives wider field of view
B. Inverts image
C. Magnifies image
D. Gives real image
Answer: Option A
Solution (By JKSSB Mock Tests)
Convex mirror diverges rays, gives erect, diminished, virtual image with wider field. Concave would magnify but narrow field. Plane gives normal view. Safety advantage.

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Practice More Physics Questions

Question #1
Two resistors in series have equivalent 6 Ω, in parallel 4/3 Ω. Individual resistors are
A. 3 Ω and 3 Ω
B. 2 Ω and 4 Ω
C. 1 Ω and 5 Ω
D. 2 Ω and 2 Ω

Correct Answer: Option B


Explanation:
Series: R1+R2=6. Parallel: (R1×R2)/(6)=4/3 => R1R2=8. Solving: R1,R2 = 2,4.

This question belongs to: Science Physics
Question #2
An engine pumps water continuously through a hose. Water leaves the hose with a velocity 'v' and mass per unit length is 'm'. What is the power imparted to the water?
A. mv^3
B. 1/2 m^2v
C. mv^2
D. 1/2 mv^3

Correct Answer: Option D


Explanation:
Power is the rate of doing work or imparting kinetic energy (dK/dt). Mass exiting per second = m * v (mass/length * length/time). Kinetic energy imparted per second = 1/2 * (mass per second) * v^2 = 1/2 * (mv) * v^2 = 1/2 * m * v^3. This is a very common advanced mechanics question.

This question belongs to: Science Physics
Question #3
Resistance of wire: R = ρL/A. If length tripled and area doubled, new R is:
A. 3R
B. 1.5R
C. R/6
D. 6R

Correct Answer: Option B


Explanation:
R' = ρ(3L)/(2A) = (3/2)(ρL/A) = 1.5R. Resistance scales directly with length, inversely with area. Memory aid: 'R ∝ L/A; changes multiply'. Proportional reasoning problem testing resistance formula, frequently appearing in competitive electricity sections.

This question belongs to: Science Physics