JEE MAIN - Physics (2022 - 27th July Morning Shift - No. 13)
A beam of light travelling along $$X$$-axis is described by the electric field $$E_{y}=900 \sin \omega(\mathrm{t}-x / c)$$. The ratio of electric force to magnetic force on a charge $$\mathrm{q}$$ moving along $$Y$$-axis with a speed of $$3 \times 10^{7} \mathrm{~ms}^{-1}$$ will be :
(Given speed of light $$=3 \times 10^{8} \mathrm{~ms}^{-1}$$)
1 : 1
1 : 10
10 : 1
1 : 2
Explanation
Ratio $$ = {{|q\overrightarrow E |} \over {|q\overrightarrow v \times \overrightarrow B |}}$$
$$ = {E \over {vB}} = {{{v_{wave}}} \over v}$$
$$\Rightarrow$$ Ratio $$ = {{3 \times {{10}^8}} \over {3 \times {{10}^7}}} = 10$$
Comments (0)
