1
JEE Main 2021 (Online) 20th July Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
If $$\overrightarrow A $$ and $$\overrightarrow B $$ are two vectors satisfying the relation $$\overrightarrow A $$ . $$\overrightarrow B $$ = $$\left| {\overrightarrow A \times \overrightarrow B } \right|$$. Then the value of $$\left| {\overrightarrow A - \overrightarrow B } \right|$$ will be :
A
$$\sqrt {{A^2} + {B^2} + \sqrt 2 AB} $$
B
$$\sqrt {{A^2} + {B^2}} $$
C
$$\sqrt {{A^2} + {B^2} - \sqrt 2 AB} $$
D
$$\sqrt {{A^2} + {B^2} + 2AB} $$
2
JEE Main 2021 (Online) 20th July Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
The entropy of any system is given by
$$S = {\alpha ^2}\beta \ln \left[ {{{\mu kR} \over {J{\beta ^2}}} + 3} \right]$$ where $$\alpha$$ and $$\beta$$ are the constants. $$\mu$$, J, k and R are no. of moles, mechanical equivalent of heat, Boltzmann constant and gas constant respectively.
[Take $$S = {{dQ} \over T}$$]
Choose the incorrect option from the following :
A
$$\alpha$$ and J have the same dimensions.
B
S and $$\alpha$$ have different dimensions
C
S, $$\beta$$, k and $$\mu$$R have the same dimensions
D
$$\alpha$$ and k have the same dimensions
3
JEE Main 2021 (Online) 20th July Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
AC voltage V(t) = 20 sin$$\omega$$t of frequency 50 Hz is applied to a parallel plate capacitor. The separation between the plates is 2 mm and the area is 1 m2. The amplitude of the oscillating displacement current for the applied AC voltage is _________. [Take $$\varepsilon $$0 = 8.85 $$\times$$ 10$$-$$12 F/m]
A
55.58 $$\mu$$A
B
21.14 $$\mu$$A
C
27.79 $$\mu$$A
D
83.37 $$\mu$$A
4
JEE Main 2021 (Online) 20th July Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
Region I and II are separated by a spherical surface of radius 25 cm. An object is kept in region I at a distance of 40 cm from the surface. The distance of the image from the surface is :

JEE Main 2021 (Online) 20th July Morning Shift Physics - Geometrical Optics Question 101 English
A
55.44 cm
B
18.23 cm
C
9.52 cm
D
37.58 cm
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