1
COMEDK 2022
MCQ (Single Correct Answer)
+1
-0

If K$$_1$$ and K$$_2$$ are maximum kinetic energies of photoelectrons emitted when lights of wavelengths $$\lambda_1$$ and $$\lambda_2$$, respectively incident on a metallic surface and $$\lambda_1=3\lambda_2$$, then

A
$${K_1} > \left( {{{{K_2}} \over 3}} \right)$$
B
$${K_1} < \left( {{{{K_2}} \over 3}} \right)$$
C
$${K_1} = 2{K_2}$$
D
$${K_2} = 2{K_1}$$
2
COMEDK 2022
MCQ (Single Correct Answer)
+1
-0

A car is moving with a speed of 54 km/h. If after 3 s, the driver applies brakes and it stops, then how much distance is covered by the car before coming to rest?

A
22.5 m
B
20 m
C
25 m
D
45.2 m
3
COMEDK 2022
MCQ (Single Correct Answer)
+1
-0

A source of sound emits sound waves at frequency $$f_0$$. It is moving towards an observer with fixed speed $${v_s}$$ ($${v_s},v$$, where $$v$$ is the speed of sound in air.) If the observers were to move towards the source with speed $$v_0$$, one of the following two graphs (A and B) will give the correct variation of the frequency $$f$$ heard by the observer as $$v_0$$ is changed.

COMEDK 2022 Physics - Waves Question 7 English

The variation of $$f$$ with $$v_0$$ is given correctly by

A
graph A with slope $$ = {{{f_0}} \over {(v + {v_s})}}$$
B
graph B with slope $$ = {{{f_0}} \over {(v - {v_s})}}$$
C
graph A with slope $$ = {{{f_0}} \over {(v - {v_s})}}$$
D
graph B with slope $$ = {{{f_0}} \over {(v + {v_s})}}$$
4
COMEDK 2022
MCQ (Single Correct Answer)
+1
-0

In which mode of transmission, the heat waves travel along straight line with the speed of light?

A
Thermal radiation
B
Forced convection
C
Natural convection
D
Thermal conduction
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