1
MHT CET 2020 19th October Evening Shift
MCQ (Single Correct Answer)
+1
-0

An electron moves in a circular orbit with uniform speed $v$. It produces a magnetic field $B$ at the centre of the circle. The radius of the circle is [ $\mu_0=$ permeability of free space, $e=$ electronic charge]

A
$\left(\frac{\mu_0 e v}{4 \pi B}\right)^{1 / 2}$
B
$\frac{\mu_0 e B}{4 \pi v}$
C
  $\frac{\mu_0 e V}{4 \pi B}$
D
$\left(\frac{\mu_0 e v}{B}\right)^{1 / 2}$
2
MHT CET 2020 19th October Evening Shift
MCQ (Single Correct Answer)
+1
-0

If the maximum kinetic energy of emitted electrons in photoelectric effect is $3.2 \times 10^{-19} \mathrm{~J}$ and the work-function for metal is $6.63 \times 10^{-19} \mathrm{~J}$, then stopping potential and threshold wavelength respectively are

[Planck's constant, $h=6.63 \times 10^{34} \mathrm{~J}$-s]

[Velocity of light, $c=3 \times 10^8 \frac{\mathrm{~m}}{\mathrm{~s}}$ ]

[Charge on electron $=1.6 \times 10^{-19} \mathrm{C}$ ]

A
4V, 6000$\mathop A\limits^o$
B
3V, 4000$\mathop A\limits^o$
C
2V, 3000$\mathop A\limits^o$
D
1V, 1000$\mathop A\limits^o$
3
MHT CET 2020 19th October Evening Shift
MCQ (Single Correct Answer)
+1
-0

The root mean square velocity of molecules of a gas is $200 \mathrm{~m} / \mathrm{s}$. What will be the root mean square velocity of the molecules, if the molecular weight is doubled and the absolute temperature is halved?

A
$50 \mathrm{~m} / \mathrm{s}$
B
$200 \mathrm{~m} / \mathrm{s}$
C
$100 \mathrm{~m} / \mathrm{s}$
D
$\frac{100}{\sqrt{2}} \mathrm{~m} / \mathrm{s}$
4
MHT CET 2020 19th October Evening Shift
MCQ (Single Correct Answer)
+1
-0

Earth has mass $M_1$ and radius $R_1$. Moon has mass $M_2$ and radius $R_2$. Distance between their centre is $r$. A body of mass $M$ is placed on the line joining them at a distance $\frac{r}{3}$ from centre of the earth. To project the mass $M$ to escape to infinity, the minimum speed required is

A
$\left[\frac{3 G}{r}\left(M_1+\frac{M_2}{2}\right)\right]^{\frac{1}{2}}$
B
$\left[\frac{6 G}{r}\left(M_1+\frac{M_2}{2}\right)\right]^{\frac{1}{2}}$
C
$\left[\frac{6 G}{r}\left(M_1-\frac{M_2}{2}\right)\right]^{\frac{1}{2}}$
D
$\left[\frac{3 G}{r}\left(M_1-\frac{M_2}{2}\right)\right]^{\frac{1}{2}}$
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