1
KCET 2019
MCQ (Single Correct Answer)
+1
-0

The magnetic fields at the centre O in the given figure is

KCET 2019 Physics - Moving Charges and Magnetism Question 19 English

A
$$\frac{7}{14} \frac{\mu_0 I}{R}$$
B
$$\frac{5}{12} \frac{\mu_0 I}{R}$$
C
$$\frac{3}{10} \frac{\mu_0 I}{R}$$
D
$$\frac{\mu_0 I}{12 R}$$
2
KCET 2018
MCQ (Single Correct Answer)
+1
-0
The correct Biot-Savart law in vector form is
A
$d \mathbf{B}=\frac{\mu_0}{4 \pi} \cdot \frac{l(d \mathbf{} \times \mathbf{r})}{r^2}$
B
$d \mathbf{B}=\frac{\mu_0}{4 \pi} \cdot \frac{\mid(d \mathbf{} \mathbf{~} \times \mathbf{r})}{r^3}$
C
$d \mathbf{B}=\frac{\mu_0}{4 \pi} \cdot \frac{|d|}{r^2}$
D
$d \mathbf{B}=\frac{\mu_0}{4 \pi} \cdot \frac{|d|}{r^3}$
3
KCET 2018
MCQ (Single Correct Answer)
+1
-0
An electron is moving in a circle of radius $r$ in a uniform magnetic field $B$. Suddenly, the field is reduced to $\frac{B}{2}$. The radius of the circular path now becomes
A
$\frac{r}{2}$
B
$2 r$
C
$\frac{r}{4}$
D
$4 r$
4
KCET 2018
MCQ (Single Correct Answer)
+1
-0
A charge $q$ is accelerated through a potential difference $V$. It is then passed normally through a uniform magnetic field, where it moves in a circle of radius $r$. The potential difference required to move it in a circle of radius $2 r$ is
A
$2 V$
B
4 V
C
1 V
D
$3 V$
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