Select Page

## 5.154 Charge of elementary particles

Problem 5.154:What is the charge of $(i)$ electron $(ii)$ proton and $(iii)$ neutron? Solution: Charge of $(i)$ electron$= - \:1.6 \times 10^{-19}\:C$                            $(ii)$ Proton$= + \:1.6 \times 10^{-19}\:C$                            $(iii)$ Neutron=...

## 5.153 Power dissipation in RC circuit

Problem 1.153: Determine the rate of energy dissipation in the given circuit at steady state. Solution: Current flows in a capacitor only when it is charging or discharging. At steady state situations current through capacitor is zero. So the given circuit can be...

## 5.152 Energy stored in capacitor

Problem 1.152: Determine the energy stored in the capacitor in the given circuit at steady state. Solution: Current flows in a capacitor only when it is charging or discharging. At steady state situations current through capacitor is zero. So the given circuit can be...

## 5.151 Charge in a capacitor

Problem 1.151: Determine the charge in the capacitor in the given circuit at steady state. Solution: Current flows in a capacitor only when it is charging or discharging. At steady state situations current through capacitor is zero. So the given circuit can be redrawn...

## 5.150 Current in RC circuit

Problem 1.150: Determine the current flowing from the cell in the given circuit at steady state. Solution: Current flows in a capacitor only when it is charging or discharging. At steady state situations current through capacitor is zero. So the given circuit can be...

## 5.149 Impedance of a circuit containing resistor, capacitor and inductor

Problem 5.149: A circuit has resistor of $100\:\Omega$, inductor of reactance $100\:\Omega$ and a capacitor of reactance $100\:\Omega$ connected in series to an alternating voltage with 200 V of rms potential. Determine the current in the circuit. Solution: The...

## 5.148 Energy stored in electric and magnetic fields in LC oscillator

Problem 5.148: A $10\:\mu\:F$ capacitor with an initial charge of $1\:\mu C$ is connected across a $40\:mH$ inductance coil. Determine the time after which the energy is completely transferred in to the inductor for the first time. Neglect resistance and poser losses....

## 5.147 Induced e.m.f in a straight rod

Problem 5.147: A composite conductor is moving with a  speed of V as shown in the diagram. The magnetic field is inward to the plane and has a constant strength of B everywhere. Find the potential difference induced in the rod.  Solution: When a straight conductor of...

## 5.145 Frequency of current in ac generator

Problem 5.145: The armature of an ac generator is rotated with a speed of 3000 rotations per minute. What will be the frequency of current produced in it? Solution: When a coil with $N$ number of turns each of area $A$ is rotated in a magnetic field $B$ with an...

## 5.144 Mutual induction between a pair of circular coils

Problem 5.144: A circular coil of radius $r$ is kept at the center of another circular coil of very large radius $R$ as shown. Determine the mutual induction between the coils. Solution: If a current $i$ is established in one coil, the current produces a magnetic flux...

## 5.143 Magnetic flux linkage between two circular coils

Problem 5.143: A circular coil of radius $r$ is kept at the center of another circular coil of very large radius $R$ as shown. Current $I$ flows in the larger coil. What is the magnetic flux linked with the inner coil? Solution: The current in the larger coil will...

## 5.142 Time period of a bar magnet in a magnetic field

Problem 5.142: A magnetic needle has magnetic moment $6.7\times 10^2\: Am^2$ and moment of inertia $7.5\times 10^6\: kg m^2$. It performs $10$ complete oscillations in $6.70\: s$. What is the magnitude of the magnetic field? Solution: Time period is the time taken for...

## 5.141 Potential energy of a dipole in a magnetic field

Problem 5.141: Four identical magnets are placed in a uniform magnetic field as shown. Which magnet possesses the minimum potential energy?   Solution: If a magnet of magnetic moment $\vec{M}$ is placed in a uniform magnetic field of intensity $\vec{B}$, then the...

## 5.140 Field detector in the magnetic field of a current carrying wire

Problem 5.140: A straight wire carries a time-dependent current of $4\:t^2$ and is placed along the y axis of a the coordinate system. A magnetic field detector is placed at a distance r from the wire on the x axis. Determine the speed of the detector along the...

## 5.139 Magnetic field due to current carrying conductor

Problem 5.139: A straight wire carries a steady current of $10\:A$ and is placed along the y axis of a the coordinate system. Determine the magnitude and direction of the magnetic field at a point $(4\:m, 0)$. Solution: Magnetic field due to a very long thin wire...

## 5.138 Magnetic moment of a solenoid

Problem 5.138: A closely wound solenoid of 2000 turns and area of cross-section $1.6\times 10^{-4}\: m^2$, carrying a current of $4.0 \:A$, is suspended through its center allowing it to turn in a horizontal plane. What is the magnetic moment associated with the...

## 5.137 Magnetic moment of a needle

Problem 5.137: A thin needle of magnetic moment $M$ is bend into a semicircle. What is the new magnetic moment? Solution: Magnetic moment of a magnet is defined as the product of pole strength and shortest distance between its poles. Let the length of the magnetic...

## 5.136 Coercivity of a subbstance

Problem 5.136: A current of $1A$ flowing in the 1000 turns of a solenoid of length $10\:cm$ can completely demagnetize a  soft iron bar of length $4\:cm$ and area of cross section of $2\:cm^2$. Determine the coercivity of the material. Solution: Coercivity is the...