A coil of cross-sectional area $10^2 cm^2$ is is placed in the magnetic field, which changes by $4×10^2\, Wb/m^2$ within 5 sec. What will be the current across 5 Ω resistance?
Answer & explanation
Correct answer: option 2
The correct answer is Option 2 → 0.16 A
Cross-Sectional Area, A=$10^2 cm^2$ =$10^2 $ × $10^{-4}m^2$=$0.01m^2$
Change in magnetic field, $ΔB=4×10^2Wb/m^2$
Time interval, $t=5s$
Resistance, $R=5Ω$
Calculate change in Magnetic flux $Δ\phi$
Magnetic flux $\phi=B×A$
So, change in magnetic flux,
$Δ\phi=A×ΔB=0.01×4×10^2=0.01×400=4.Wb$
Calculate induced emf (Faraday's law)
$Emf=\frac{Δ\phi}{t}=\frac{4}{5}=0.8V$
Calculate current using ohm's law
$I=\frac{Emf}{R}=\frac{0.8}{5}=0.16A$