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Current electricity: Resistance, Drift speed

Q- A solid cube of silver (density = 10.5 g/ cm3) has a mass of 90.0 g.

(a) What is the resistance between opposite faces of the cube?

(b) Assuming each silver atom contributes one conduction electron, find the average drift speed of electrons when a potential difference of 1.00*1O-5V is applied t…

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Potential Divider

Q- A 20V battery has an internal resistance r = 2 ohms. Design a voltage divider supplying 5V (Open circuit) from the end-points of resistor R2 = 10 ohms. Find the load current when RL = 15 ohms is connected to the R2 of the divider and the voltage under load.

Solution:

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Resistance -series and parallel

Q- Two resistors connected in series have an equivalent resistance of 690 W. When they are connected in parallel, their equivalent resistance is 150 W. Find the resistance of each resistor.

Solution:

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Current in lightning

(On request - Kylie)

Q- The potential difference between a storm cloud and the ground is 100 million volts. A charge of 2 coulomb flashes in a lightning bolt from cloud to earth. How much current is in the lightning flash, if it lasted for 0.1 second?

Solution:

The current is the rate of flow of…

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Potentiometer- Internal resistance

Q- The circuit below shows a circuit designed to measure the internal resistance ‘r’ of a battery. Resistor R is 2Ω and AB is the potentiometer wire. With the switch S open a balancing length l1 = 55.2cm is obtained. When switch S is closed the balancing length becomes l2 = 53.2cm. Calculate th…

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Network (Resistances)

Q- Consider the circuit below.

a) Find the equivalent resistance of the combination.

b) If a 10V potential difference (PD) is applied across the points A and B, find the PD across the 4Ω resistor and current in it.

Solution:

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Kirchhoff's Law

Q. Consider the circuit below.

a) Reduce the circuit to a two loop circuit and redraw the circuit showing the directions of the currents I1, I2 and I3. (Take I2 to flow through the central section of the circuit).

b) Using two clockwise traverse loops for the left and right sections of the circu…

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Current Electricity

Q- In the circuit below

a) Find the current in the 4Ω resistor.

b) What is the power dissipated in this resistor?

Solution:

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Kirchhoff's Law

Q- Consider the circuit give bellow -

a) Neglecting the internal resistances of the batteries, find the current in the circuit.

b) What power is delivered to each of the resistors?

c) What power is delivered by the 12V battery?

d)What power is delivered by 6V battery?

Solution:

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Current Electricity

Q- A 2.8 kΩ and a 2.1 kΩ resistor are connected in parallel; this combination is connected in series to a 1.8 kΩ resistor. If each resistor is rated at 0.50 W, what is the maximum voltage that can be applied across the whole network without damaging resistors?

Solution:

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EMF

(On request – Nicol)

Q- A dry cell (battery) does 7.12 J of work through chemical energy to transfer 5.92 C of charge between the terminals of the cell. What is the electric potential difference between the two terminals? 

Solution:

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Current Electricity- Power

(On request -Te'Shia)

Q- A 12 V battery holds 100 J of energy. It discharges all of this energy at a steady rate over the course of 2 hours while powering a flashlight. How much power did the battery deliver to the flashlight? What was the current?

Solution:

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Current Electricity

Q- Four resistors (R1 = 60 Ohms, R2 = 220 Ohms, R3 = 330 Ohms, and R4 = 480 Ohms), an ideal inductor (L = 8 mH), and a capacitor (C = 250 µF) are connected to a battery (V = 9V) through a switch as shown in the figure below. What is Ustored, the total stored energy in the circuit elements (not incl…

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Resitance and Resistivity

Q- An aluminum rod has a resistance of 1.234 Ohm at 20.0°C. Calculate the resistance of the rod at 120°C by accounting for the changes in both the resistivity and its dimensions. (Resistivity of aluminum at 200C is 2.75*10-8 Ohm.m, temperature coefficient of resistivity is 4.4*10-3/0C and the coef…

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Current Electricity

Drift Speed

(On request- Sunanda)

Q- An aluminum wire having a cross-sectional area of 6.00*10-6 m2 carries a current of 3.70 A. Find the drift-speed of the electrons in the wire. The density of aluminum is 2.70 g/cm3. Assume that one conduction electron is supplied by each atom.

Solution:

 

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Current Electricity

Q1- In the construction of an electrical circuit a 5.00 µF capacitor was accidentally used instead of the required 16.0 µF capacitor? What value capacitor must a technician add to correct this circuit without removing existing circuit elements? Must any connections be broken in the process?

Q2- T…

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Current electricity

Q1- a) What is the resistance of a light bulb that uses 75 Watts at 115 Volts?   b) What is the current in the bulb in this situation?

Q2- An electric heater is designed to consume 600 W when connected to a 120 V line. How much power is actually used if line voltage is only 110 V?

Q3- A 6V, 3W l…

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Electric current

Q1- During the time interval between t = 0 and t = 17 s, the total charge that crossed a plane across a wire at time t is given by (16C)(1-e-t/5.8s)where t is in seconds. What is the maximum value of the current? What is the current at t = 5.8 s?

Q2- A tube of mercury with a resistivity of 9.84 x…

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Current density

Q1- Suppose a current of I = 1 A flows through a conductor that is tapered. The initial diameter of the conductor is 1 mm with a length of 5 mm. The final diameter of the conductor is 3 mm with a length of 8 mm, the tapered section in between is 10 mm long. (a) What is the current density through al…

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