Explain the advantages of a transformer having an isolated secondary.

What is the assumed value of $k$ for an iron-core transformer?

Two coils are mutually coupled, with L1=50 mH, L2=120 mH, and k=0.5. Calculate the maximum possible equivalent inductance if the coils are connected in parallel

A coil, $L_1$, produces $200\space\mu\text{Wb}$ of magnetic flux. A nearby coil, $L_2$, is linked with $L_1$ by $50\space\mu\text{Wb}$ of magnetic flux. What is the coefficient of coupling, $k$, between $L_1$ and $L_2$?

How much is the self-induced voltage across a $33\text{-mH}$ inductance when the current changes at the rate of $1500\space\frac{\text{A}}{\text{s}}$?

Calculate the inductance, $L$, for the following long coils: (Note: $1\text{ m}=100\text{ cm}$ and $1\text{ m}^2=10,000\text{ cm}^2$.) a. air core, $20$ turns, area $3.14\text{ cm}^2$, length $25\text{ cm}$. b. same coil as step a with ferrite core having a $\mu_\text{r}$ of $5000$. c. air core, $200$ turns, area $3.14\text{ cm}^2$, length $25\text{ cm}$. d. air core, $20$ turns, area $3.14\text{ cm}^2$, length $50\text{ cm}$. e. iron core with $\mu_\text{r}$ of $2000$, $100$ turns, area $5\text{ cm}^2$, length $10\text{ cm}$.

If the bleeder current, $I_\text{B}$, is $15\text{ mA}$ in Fig. 7–32, solve for a. $I_1$, $I_2$, $I_3$, and $I_\text{T}$. b. $V_1$, $V_2$, and $V_3$. c. $R_1$, $R_2$, and $R_3$. d. The power dissipated by $R_1$, $R_2$, and $R_3$.

A transformer delivers $400\text{ W}$ to a load connected to its secondary. If the input power to the primary is $500\text{ W}$, what is the efficiency of the transformer?

Conjugate the verb in the present active and passive voice and give the present active and passive infinitives: credo, credere, credidi, creditum

How much is the self-induced voltage, $V_\text{L}$, across a $100\text{-mH}$ inductor produced by a current change of $50,000\space\frac{\text{A}}{\text{s}}$? a. $5\text{ kV}$. b. $50\text{ V}$. c. $5\text{ MV}$. d. $500\text{ kV}$.

Two $10\text{-H}$ inductors are connected in series-aiding and have a mutual inductance, $L_\text{M}$, of $0.75\text{ H}$. The total inductance, $L_\text{T}$, of this combination is a. $18.5\text{ H}$. b. $20.75\text{ H}$. c. $21.5\text{ H}$. d. $19.25\text{ H}$.

In Fig. 19–37, solve for a. the turns ratio $\dfrac{\text{N}_\text{P}}{\text{N}_\text{s}}$. b. the secondary current, $I_\text{S}$. c. the primary current, $I_\text{P}$.

Based on brain scans of those with bipolar disorder, which of the following is true? a. The brain is more active during manic episodes and less active during depressive episodes. b. The brain is less active during manic episodes and more active during depressive episodes. c. There is no consistent relationship between brain activity and periods of mania or depression. d. The brain is more active than normal during both manic and depressive episodes. e. The brain is less active than normal during both manic and depressive episodes.

In Fig. 19–36, solve for a. $V_{\text{S}_{1}}$ (secondary 1 voltage). b. $V_{\text{S}_{2}}$ (secondary 2 voltage). c. $I_{\text{S}_{1}}$ (secondary 1 current). d. $I_{\text{S}_{2}}$ (secondary 2 current). e. $P_{\text{Sec}_{1}}$. f. $P_{\text{Sec}_{2}}$. g. $P_{\text{pri}_{1}}$. h. $I_\text{P}$.