Start learning →

B.Tech EEE Electric Current, Resistance, and Ohm's Law — practice questions — page 2

Explore 90 free Electric Current, Resistance, and Ohm's Law questions in B.Tech EEE Electrical Engineering. Open each question or exercise to read its content, reference answers and available explanation.

Practise Electric Current, Resistance, and Ohm's Law with Quill →

Electric Current, Resistance, and Ohm's Law questions and exercises with answers

Showing questions 31–60 of 90.

Which statement about the resistivity of a substance is correct?Read the answer and worked solution →How do conductors, semiconductors and insulators rank by resistivity?Read the answer and worked solution →Copper has resistivity 1.72 x 10^-8 ohm m. What is the resistance of 20.0 m of 12-gauge copper wire of diameter 2.053 mm?Read the answer and worked solution →A tungsten filament of resistivity 5.6 x 10^-8 ohm m is a cylinder 4.00 cm long with a cold resistance of 0.350 ohm. What is its diameter?Read the answer and worked solution →Why does the resistivity of a metal rise as its temperature rises?Read the answer and worked solution →Which alloy has a temperature coefficient of resistivity close to zero, making it suitable for a temperature-independent resistance standard?Read the answer and worked solution →A tungsten filament of resistance 0.350 ohm at 20 degrees C is heated to 2850 degrees C. Taking alpha as 4.5 x 10^-3 per degree C, what is its hot resistance?Read the answer and worked solution →To what Celsius temperature must a copper wire starting at 20.0 degrees C be raised to double its resistance, if alpha is 3.9 x 10^-3 per degree C?Read the answer and worked solution →A thermistor used in a digital medical thermometer is which of these?Read the answer and worked solution →Electric power delivered to a device is the product of which two quantities?Read the answer and worked solution →A 25-W bulb and a 60-W bulb both run on the same voltage. How do they compare?Read the answer and worked solution →Reading P = V squared / R for a fixed supply voltage, what happens as the connected resistance falls?Read the answer and worked solution →A 25-W bulb designed for 120 V is connected to 240 V. If its resistance stayed constant, what power would it draw?Read the answer and worked solution →A headlight has a cold resistance of 0.350 ohm and 12.0 V is applied at the instant it is switched on. What power does it dissipate then?Read the answer and worked solution →That same cold headlight dissipates 411 W across 0.350 ohm. What current flows at that moment?Read the answer and worked solution →Of the three power expressions, which one holds for any device and not only for resistors?Read the answer and worked solution →One kilowatt hour of electrical energy equals how many joules?Read the answer and worked solution →Electricity costs 12 cents per kilowatt hour. What does it cost to run a 60-W incandescent bulb for 1000 hours?Read the answer and worked solution →A 60-W incandescent bulb is replaced by a compact fluorescent lamp of the same brightness. What is the wattage of the replacement?Read the answer and worked solution →Alternating current is best described as which of these?Read the answer and worked solution →A battery holds its terminal voltage constant. What kind of current does it establish once the circuit settles?Read the answer and worked solution →In the quantities rms current and rms voltage, what does rms stand for?Read the answer and worked solution →Why is a root mean square average used for an AC waveform rather than a plain time average?Read the answer and worked solution →What do the quoted rms current, rms voltage and average power of an AC supply represent?Read the answer and worked solution →Household mains is quoted as 120 V AC. What is its peak voltage?Read the answer and worked solution →Heavy industrial equipment runs on AC with a peak voltage of 679 V. What is the rms voltage?Read the answer and worked solution →A circuit breaker trips at an rms current of 15.0 A. What peak current does that correspond to?Read the answer and worked solution →An AC light bulb has an average power consumption of 60.0 W. What is its peak power?Read the answer and worked solution →What current is needed to transmit 100 MW of power at 200 kV?Read the answer and worked solution →That 500 A flows through transmission lines of total resistance 1.00 ohm. What power is dissipated in the lines?Read the answer and worked solution →

Worked practice questions

Which statement about the resistivity of a substance is correct?

  1. It depends on the object's length
  2. It depends on the object's area
  3. It is measured in ohms per ampere
  4. It is independent of shape and size
Show answer and solution

Correct answer: D. It is independent of shape and size

1. Resistance R belongs to a particular object and changes if you cut or stretch it. 2. Resistivity rho belongs to the material itself and is an intrinsic property. 3. It stays the same whatever shape or size the sample is cut to. 4. Shape enters only through R = rho L / A, where L and A describe the object rather than the material. _Source: OpenStax College Physics (CC BY 4.0), Ch 20 "Electric Current, Resistance, and Ohm's Law", section 20.3 Resistance and Resistivity_

Open this question →

How do conductors, semiconductors and insulators rank by resistivity?

  1. Conductors lowest, insulators highest
  2. Insulators lowest, conductors highest
  3. Semiconductors lowest, metals highest
  4. All three groups share one value range
Show answer and solution

Correct answer: A. Conductors lowest, insulators highest

1. Materials are grouped into three broad bands by the size of their resistivity. 2. Conductors have the smallest resistivities because they carry large free charge densities. 3. Insulators have the largest, because almost all their charges are bound to atoms. 4. Semiconductors sit between the two, with far fewer free charges than a conductor. 5. Reversing the order, as in option two, would make copper an insulator and rubber a wire. _Source: OpenStax College Physics (CC BY 4.0), Ch 20 "Electric Current, Resistance, and Ohm's Law", section 20.3 Resistance and Resistivity_

Open this question →

Copper has resistivity 1.72 x 10^-8 ohm m. What is the resistance of 20.0 m of 12-gauge copper wire of diameter 2.053 mm?

  1. 0.208 ohm
  2. 0.052 ohm
  3. 1.04 ohm
  4. 0.104 ohm
Show answer and solution

Correct answer: D. 0.104 ohm

1. Use R = rho L / A for a uniform cylinder. 2. The radius is half the diameter, r = 1.0265 x 10^-3 m. 3. A = pi r^2 = 3.310 x 10^-6 m^2. 4. Numerator: rho L = (1.72 x 10^-8 ohm m)(20.0 m) = 3.44 x 10^-7 ohm m^2. 5. R = (3.44 x 10^-7 ohm m^2) / (3.310 x 10^-6 m^2) = 0.104 ohm. 6. 0.052 ohm is what you get by using the full diameter as the radius, which doubles the area. 7. 1.04 ohm is a factor of ten out and would make ordinary house wiring waste noticeable power. _Source: OpenStax College Physics (CC BY 4.0), Ch 20 "Electric Current, Resistance, and Ohm's Law", section 20.3 Resistance and Resistivity_

Open this question →

How to practise

  1. Choose a Electric Current, Resistance, and Ohm's Law question and try to work out your answer.
  2. Open the question to check the correct answer and read its worked solution.
  3. Continue in the app for bite-sized lessons, explanations and review with Quill. You can start without creating an account.

More Electrical Engineering topics

MagnetismCircuits and DC Instruments