Question

Figure shows voltage and current graphs for a resistor.

a. What is the emf frequency $f$?

b. What is the value of the resistance $R$?

c. Draw the resistor’s voltage and current phasors at $t=15ms$

Short answer

a) Emf frequency $f=25Hz$

b) Resistance $R=20\Omega$

c) Required figure is given below.

Step-by-step solution

Part (a) Step 1 : Given information

We are given that

Time period $T=0.04s$

We have to find frequency$f$

Part(a) Step 2: Simplify

As we know,

$f=\frac{1}{T}$

$f=$Frequency

$T=$Time period

$f=\frac{1}{0.04}=25Hz$

Part(b) Step 1 : Given information

We are given that

Voltage $V_0=10V$

Current $I_0=0.5A$

We have to find Resistance

Part(b) Step 2: Simplify

$$\begin{gathered} R=\frac{V_0}{I_0} \\ R=\frac{10V}{0.5A} \\ R=20\Omega \end{gathered}$$

Part(c) Step 1: Given information

We are given that $t=15ms$ we have to draw resistor's voltage.

Part(c) Step 2: Simplify

As we know,

$$\begin{gathered} wt=2\pi f\left(15\times {10}^{-3}\right) \\ wt=2\pi \left(25\right)\left(15\times {10}^{-3}\right) \\ wt={135}^{\circ } \end{gathered}$$

Required graph :