1
JEE Main 2022 (Online) 27th July Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

Two sources of equal emfs are connected in series. This combination is connected to an external resistance R. The internal resistances of the two sources are $$r_{1}$$ and $$r_{2}$$ $$\left(r_{1}>r_{2}\right)$$. If the potential difference across the source of internal resistance $$r_{1}$$ is zero, then the value of R will be :

A
$$r_{1}-r_{2}$$
B
$$\frac{r_{1} r_{2}}{r_{1}+r_{2}}$$
C
$$\frac{r_{1}+r_{2}}{2}$$
D
$$r_{2}-r_{1}$$
2
JEE Main 2022 (Online) 27th July Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

A direct current of $$4 \mathrm{~A}$$ and an alternating current of peak value $$4 \mathrm{~A}$$ flow through resistance of $$3\, \Omega$$ and $$2\,\Omega$$ respectively. The ratio of heat produced in the two resistances in same interval of time will be :

A
3 : 2
B
3 : 1
C
3 : 4
D
4 : 3
3
JEE Main 2022 (Online) 27th July Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

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 $$=3 \times 10^{8} \mathrm{~ms}^{-1}$$)

A
1 : 1
B
1 : 10
C
10 : 1
D
1 : 2
4
JEE Main 2022 (Online) 27th July Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

A microscope was initially placed in air (refractive index 1). It is then immersed in oil (refractive index 2). For a light whose wavelength in air is $$\lambda$$, calculate the change of microscope's resolving power due to oil and choose the correct option.

A
Resolving power will be $$\frac{1}{4}$$ in the oil than it was in the air.
B
Resolving power will be twice in the oil than it was in the air.
C
Resolving power will be four times in the oil than it was in the air.
D
Resolving power will be $$\frac{1}{2}$$ in the oil than it was in the air.
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