1
JEE Main 2020 (Online) 7th January Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
If the magnetic field in a plane electromagnetic wave is given by
$$\overrightarrow B $$ = 3 $$ \times $$ 10-8 sin(1.6 $$ \times $$ 103x + 48 $$ \times $$ 1010t)$$\widehat j$$ T, then what will be expression for electric field ?
A
$$\overrightarrow E $$ = (9sin(1.6 $$ \times $$ 103x + 48 $$ \times $$ 1010t)$$\widehat k$$ V/m)
B
$$\overrightarrow E $$ = (60sin(1.6 $$ \times $$ 103x + 48 $$ \times $$ 1010t)$$\widehat k$$ V/m)
C
$$\overrightarrow E $$ = (3 $$ \times $$ 10-8 sin(1.6 $$ \times $$ 103x + 48 $$ \times $$ 1010t)$$\widehat i$$ V/m)
D
$$\overrightarrow E $$ = (3 $$ \times $$ 10-8 sin(1.6 $$ \times $$ 103x + 48 $$ \times $$ 1010t)$$\widehat j$$ V/m)
2
JEE Main 2020 (Online) 7th January Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
Visible light of wavelength 6000 $$ \times $$ 10-8 cm falls normally on a single slit and produces a diffraction pattern. It is found that the second diffraction minimum is at 60o from the central maximum. If the first minimum is produced at $$\theta $$1, then $$\theta $$1, is close to :
A
45o
B
30o
C
25o
D
20o
3
JEE Main 2020 (Online) 7th January Morning Slot
Numerical
+4
-0
Change Language
A beam of electromagnetic radiation of intensity 6.4 × 10–5 W/cm2 is comprised of wavelength, $$\lambda $$ = 310 nm. It falls normally on a metal (work function $$\phi $$ = 2eV) of surface area of 1 cm2. If one in 103 photons ejects an elctron, total number of electrons ejected in 1 s is 10x. (hc = 1240 eVnm, 1eV = 1.6 × 10–19 J), then x is _____.
Your input ____
4
JEE Main 2020 (Online) 7th January Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
A litre of dry air at STP expands adiabatically to a volume of 3 litres. If $$\gamma $$ = 1.40, the work done by air is : (31.4 = 4.6555) [Take air to be an ideal gas]
A
60.7 J
B
100.8 J
C
90.5 J
D
48 J
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