A step-up transformer increases 16 V to 120 V. What is the current in the secondary as compared to the primary? Assume $100$ percent efficiency.

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 $22.0 \mathrm{~cm}$ 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?

A transformer has 420 turns in the primary and 120 in the secondary. What kind of transformer is this and, assuming $100$ percent efficiency, by what factor does it change the voltage? By what factor does it change the current?

A transformer is designed to change 120 V into 10,000 V, and there are $5000$ turns in the primary. How many turns are in the secondary, assuming $100$ percent efficiency?

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.

Compare the oscillations of an LC circuit to the vibration of a mass m on a spring. What do L and C correspond to in the mechanical system?

In a sample of 2016 U.S. adults, 383 said Franklin Roosevelt was the best president since World War II. Two U.S. adults are selected at random without replacement. (a) Find the probability that both adults say Franklin Roosevelt was the best president since World War II. (b) Find the probability that neither adult says Franklin Roosevelt was the best president since World War II. (c) Find the probability that at least one of the two adults says Franklin Roosevelt was the best president since World War II. (d) Which of the events can be considered unusual? Explain.

A dc generator is rated at 10 kW, 200 V, and 50 A when it rotates at $1000$ rpm. The resistance of the armature windings is $0.40 ~\Omega$. (a) Calculate the "no-load" voltage at $1000$ rpm (when there is no circuit hooked up to the generator). (b) Calculate the full-load voltage (i.e. at $50 ~\mathrm{A}$) when the generator is run at $800$ rpm. Assume that the magnitude of the magnetic field remains constant.