# ## Solution Search

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August 4, 2021
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September 8, 2017

## . : "EMI"

### Electromagnetism: Induced EMF

Q- A solenoid has length L = 30 cm, radius 6 cm, and N1 = 5500 turns; its axis coincides with the z-axis. A circular conducting loop containing N2 = 15 turns of radius a = 3 cm is centered inside the solenoid; the plane of the loop makes a 30° angle with respect to the z-axis. The loop has a net res…

### Induced EMF in an Inductor

Q4. A current i through a 0.5 H inductor vary with time t as shown by the graph below. Find the magnitude of the induced emf for the time interval

(a) t = 0 to t = 2 ms. You can ignore the behavior at the ends of the intervals.

(b) t = 2 to t = 5 ms.

(c) t = 5 to t =6 ms. Solution:

### Electromagnetic Induction: Transformer

Q- A step-down transformer is used for recharging the batteries of portable devices. The turns ratio inside the transformer is 13:1 and it is used with 120-V (rms) household service. If particular ideal transformer draws 0.350 A from the house outlet, what are

(a) The voltage

(b) The current suppl…

Q- A coil consists of 200 turns. Each turn is a square of wire of side 18cm. A magnetic field produced by an electro-magnet and directed perpendicular to the plane of the coil is switched on. If the field changes linearly from 0 to 0.5T in 0.8s:

(a) What is the induced emf in the coil while the fie…

Q- A coil of area 0.1m2 is rotating at 60rev/s. with its axis of rotation perpendicular to a 0.2T uniform magnetic field.

(a) If the coil has 1000 turns, what is the maximum EMF generated in it?

(b) What is the orientation of the coil with respect to the magnetic field when the maximum induced vol…

### Electromagnetic Induction.

Q- A 25 turn circular coil of wire has a diameter of 1.0m. It is placed with its axis (a line through the center of the coil at right angles to its plane) along the direction of the Earth’s magnetic field of 50 µT. The coil is then flipped in a time of 0.2s through an angle of 1800. Calculate the…

### Electromagnetic Induction

Q- A loop of wire in the shape of a rectangle of width w and length L and a long, straight wire carrying a current I lie on a tabletop as shown in figure. Suppose the current is changing with time according to I = a + b*t, where a and b are constants. Determine the emf that is induced in the loop if…

### L-C Circuit : Resonance

Q- The tuning circuit of an AM radio contains an LC combination. The inductance is 0.200 mH, and the capacitor is variable, so that the circuit can resonate at any frequency between 550 KHz and 1650 KHz. Find the range of values required for C.

Solution:

### Electromagnetic Induction

Q- An automobile has a vertical radio antenna 1.20 m long. The automobile travels at 72.0 km/h on a horizontal road where the Earth's magnetic field is 50.0 µT directed toward the north and downward at an angle of 60.0° below the horizontal. Calculate the maximum possible magnitude of EMF induced in…

### Electromagnetic Waves - Poynting vector

Q- In a region of free space at an instant of time the electric field is E =(80.0i + 32.0j – 64.0k)N/C and the magnetic field is B = (0.200i + 0.0800j + 0.290k) micro-Tesla.

a) Show that the two fields are perpendicular to each other.

b) Determine the Poynting vector for these fields.

Solution:

### Electromagnetic Waves

Q- A monochromatic light source emits 100w of electromagnetic power uniformly in all directions

a) Calculate the average electric- field energy density 1.00 m from the source.

b) Calculate the average magnetic-field energy density at the same distance from the source.

Solution:

### Transformers

Q- A high intensity desk lamp uses a bulb rated 40W but requires only 12V. It contains a transformer that converts 120V household voltages.

a) Is the transformer step-up or step-down?

b) What is the current in the secondary when the lamp is switched on?

c) What is the current in the primary when …

### Poynting Vector

Q- When a high-power laser is used in the Earth's atmosphere, the electric field of the laser beam can ionize the air, turning it into conducting plasma that reflects the laser light. In dry air at 0°C and 1 atm, electric breakdown occurs for fields with amplitudes above about 3.00 MV/m.

a) What l…

### Transformers

(On request – Colin)

Q- A step-down transformer has an output of 14.5 V and 0.66 A when connected to an incoming 268 V line. What is the ratio of primary to secondary loops?
a) What current does the transformer draw from the incoming line?
b) What is the power output of the transformer?

Solu…

### Electromagnetic Induction.

Q- An aluminum ring of radius r1 and resistance R is placed around the top of a long air-core solenoid with n turns per meter and smaller radius r2 as shown in Figure. Assume that the axial component of the field produced by the solenoid over the area of the end of the solenoid is one-half as strong…

### Electromagnetic Waves

Q- Write down expression for the electric and magnetic fields of a sinusoidal plane electromagnetic wave having a frequency of 3.00 GHz and traveling in the positive x- direction. The amplitude of the electric field is 300 V/m.

Solution:

### Electro Magnetic Induction

You have the following components with you (1) a100 mH inductor (2) a piece of copper wire (3) a light bulb and Rs 50.00 which just happens to be enough to purchase any capacitor as Radio Shack.
(A) How would you design a device, from the tools you have available above, to be able to detect Wi-Fi si…

### LC Oscillations

Q- A circuit contains a loop with an inductor and a capacitor which and produces an oscillating current. In this LC circuit, L = 3.5 mH and C = 2.6*10-6 F. At t = 0 the charge on the capacitor is zero and the current in the circuit is 1 A.

(a)What is the maximum charge Q that will appear on the cap…

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