A step-up transformer increases 25 V to 120 V. What is the current in the secondary coil as compared to the primary coil?

A transformer is designed to change 120 V into 10,000 V, and there are 164 turns in the primary coil. How many turns are in the secondary coil?

A transformer is designed to change $117 \mathrm{~V}$ into $13,500 \mathrm{~V}$, and there are $172$ turns in the primary coil. How many turns are in the secondary coil?

A coil has $2.25~\Omega$ resistance and $112 \mathrm{~mH}$ inductance. If the current is $3.00 \mathrm{~A}$ and is increasing at a rate of $3.80 \mathrm{~A} / \mathrm{s}$, what is the potential difference across the coil at this moment?

A $22.0 \mathrm{~cm}$ diameter coil consists of $30$ turns of circular copper wire $2.6 \mathrm{~mm}$ in diameter. A uniform magnetic field, perpendicular to the plane of the coil, changes at a rate of $8.65 \times 10^{-3} \mathrm{~T} / \mathrm{s}$. Determine the rate at which thermal energy is produced.

A 9.6-cm-diameter circular loop of wire is in a 1.10-T magnetic field. The loop is removed from the field in 0.15 s. What is the average induced emf?

A $22.0 \mathrm{~cm}$ diameter coil consists of $30$ turns of circular copper wire $2.6 \mathrm{~mm}$ in diameter. A uniform magnetic field, perpendicular to the plane of the coil, changes at a rate of $8.65 \times 10^{-3} \mathrm{~T} / \mathrm{s}$. Determine the current in the loop

Part of a single rectangular loop of wire with dimensions shown in Fig. 29-40 is situated inside a region of uniform magnetic field of $0.650 \mathrm{~T}$. The total resistance of the loop is $0.280 \Omega$. Calculate the force required to pull the loop from the field (to the right) at a constant velocity of $3.40 \mathrm{~m} / \mathrm{s}$. Neglect gravity.

A circular loop in the plane of the paper lies in a $0.65 \mathrm{~T}$ magnetic field pointing into the paper. The loop's diameter changes from $20.0 \mathrm{~cm}$ to $6.0 \mathrm{~cm}$ in $0.50 \mathrm{~s}$. What is the average induced current if the coil resistance is $2.5 \Omega$ ?

A circular loop in the plane of the paper lies in a $0.65~\mathrm{T}$ uniform magnetic field pointing into the paper. The loop's diameter changes from $20.0 \mathrm{~cm}$ to $8.0 \mathrm{~cm}$ in $0.50 \mathrm{~s}$. What is the direction of the induced current?

A circular loop in the plane of the paper lies in a $0.65 \mathrm{~T}$ magnetic field pointing into the paper. The loop's diameter changes from $20.0 \mathrm{~cm}$ to $6.0 \mathrm{~cm}$ in $0.50 \mathrm{~s}$. What is the magnitude of the average induced emf?

A circular loop in the plane of the paper lies in a $0.65 \mathrm{~T}$ magnetic field pointing into the paper. The loop's diameter changes from $20.0 \mathrm{~cm}$ to $6.0 \mathrm{~cm}$ in $0.50 \mathrm{~s}$. What is the direction of the induced current?

When a brushless exciter is used, what converts the AC produced in the armature winding into DC before it is supplied to the field winding?

Suppose you are holding a circular ring of wire and suddenly thrust a magnet, south pole first, away from you toward the center of the circle. Is a current induced in the wire? Is a current induced when the magnet is held steady within the ring? Is a current induced when you withdraw the magnet? In each case, if your answer is yes, specify the direction.