Question

A very long wire generates a magnetic field of 0.0020 x 104 T at a distance of 1.0 mm. What is the magnitude of the current? (1mm- 10 m. A) 1.0 mA B) 20 mA C) 4,000 mA D) 3,100 mA 1. A conductor is formed into a square of side 0.5m and placed in the horizontal y-plane. A magnetic ficld of IT is oriented making 30.0P with the plane of the coil. What is the magnetic flux through the conductor? A) 0.12T-m2 B)022T-m2 C)025T-m2 D) 20T-to2 2. s A device with a resistance of 200.o k is connected to a 10.0 V battery. How much poerdoesthedence use? (lke 10kilili-10'.) A)050W B) 200000k C) 0050 D) 2000W

Answer 1

1.

Given data

$r=1mm=10^{-3}m$

We know

$B=\frac{\mu _{o}}{2\pi }\frac{I}{r}$

$I=\frac{2\pi Br}{\mu _{o}}$

$I=\frac{2\pi \times 0.002\times 10^{-4}\times 10^{-3}}{4\pi \times 10^{-7}}A$

$I=1mA$

Hence A) is the right answer.

2.

Given data

$B=1T$

$A=(0.5\times 0.5)m^{2}=0.25m^{2}$

Angle to the normal to that plane can be given by

$\theta =60^{0}$

Electric flux through that plane can be given by

$\phi =BAcos\theta$

$\phi =(1\times 0.5\times 0.5\times cos60^{0})T.m^{2}$

$\phi =0.12T.m^{2}$

Hence A) is the right answer.

3.

Given data

$R=200k\Omega =200\times 10^{3}k\Omega$

$V=10V$

Power used by the device can be given by

$P=\frac{V^{2}}{R}$

$P=\frac{10^{2}}{200\times 10^{3}}W$

$P=0.05mW$

Hence C) is the right answer.