KCET 2019 | Moving Charges and Magnetism Question 30 | Physics

Coersivity of a magnet where the ferromagnet gets completely demagnetized is $$3 \times 10^3 \mathrm{~Am}^{-1}$$. The minimum current required to be passes in a solenoid having 1000 turns per metre, so that the magnet gets completely demagnetized when placed inside the solenoid is

30 mA

60 mA

3 A

6 A

KCET 2019

MCQ (Single Correct Answer)

-0

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

KCET 2019 Physics - Moving Charges and Magnetism Question 10 English

$$\frac{7}{14} \frac{\mu_0 I}{R}$$

$$\frac{5}{12} \frac{\mu_0 I}{R}$$

$$\frac{3}{10} \frac{\mu_0 I}{R}$$

$$\frac{\mu_0 I}{12 R}$$

KCET 2018

MCQ (Single Correct Answer)

-0

The correct Biot-Savart law in vector form is

$d \mathbf{B}=\frac{\mu_0}{4 \pi} \cdot \frac{l(d \mathbf{} \times \mathbf{r})}{r^2}$

$d \mathbf{B}=\frac{\mu_0}{4 \pi} \cdot \frac{\mid(d \mathbf{} \mathbf{~} \times \mathbf{r})}{r^3}$

$d \mathbf{B}=\frac{\mu_0}{4 \pi} \cdot \frac{|d|}{r^2}$

$d \mathbf{B}=\frac{\mu_0}{4 \pi} \cdot \frac{|d|}{r^3}$

KCET 2018

MCQ (Single Correct Answer)

-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

$\frac{r}{2}$

$2 r$

$\frac{r}{4}$

$4 r$

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