NEET UG · Physics

Current electricity

28 practice questions, each with the answer and an explanation.

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Random questions from this topic, one at a time. You see the answer and the explanation straight after each one.

All 28 questions

  1. A heater of resistance is connected to a supply. What is the power consumed (in W)?
  2. A heater of resistance is connected to a supply. What is the power consumed (in W)?
  3. A heater of resistance is connected to a supply. What is the power consumed (in W)?
  4. A cylindrical copper wire of resistance R is uniformly stretched until its length is doubled (l' = 2l) while keeping its volume constant. What is the new electrical resistance of the wire?
  5. Why does the electrical resistivity of metallic conductors increase with rising temperature, whereas the resistivity of intrinsic semiconductors decreases exponentially?
  6. What is the color code sequence on a carbon resistor having a nominal resistance of 47 kΩ ± 10%?
  7. Two electric bulbs rated 220 V, 40 W and 220 V, 100 W are connected in series across a 220 V power supply. Which bulb will glow brighter, and why?
  8. A storage battery of EMF E = 12 V and internal resistance r = 1.0 Ω is being recharged by an external DC charger with a current of 2.0 A. What is the terminal potential difference (V) across the batte…
  9. According to the Maximum Power Transfer Theorem, under what condition does an electrical source with internal resistance r deliver maximum power to a variable external load resistor R?
  10. Kirchhoff's first law (the junction rule, ΣI = 0) and Kirchhoff's second law (the loop rule, ΣΔV = 0) are direct consequences of which fundamental physical conservation laws?
  11. In a balanced Wheatstone bridge with four arms P, Q, R, and S, what is the condition for null deflection (zero current) through the central galvanometer?
  12. In a meter bridge experiment, a null point is obtained at a balancing length l = 40.0 cm from the left end when a known resistance R = 6.0 Ω is in the left gap. What is the value of the unknown resist…
  13. Why is a potentiometer universally preferred over an ordinary moving-coil voltmeter for measuring the true electromotive force (EMF) of a chemical cell?
  14. In a potentiometer circuit, a cell of EMF E1 gives a balance length l1 = 60 cm. When replaced by another cell of EMF E2, the balance length is l2 = 80 cm. What is the ratio of their electromotive forc…
  15. How can a sensitive moving-coil galvanometer of resistance G and full-scale deflection current Ig be converted into an ammeter capable of measuring a large maximum current I?
  16. How can a moving-coil galvanometer of resistance G and full-scale deflection current Ig be converted into a voltmeter capable of measuring a maximum voltage V?
  17. What is the microscopic expression for current density (J) in terms of electron charge (e), free electron number density (n), and drift velocity (vd)?
  18. A potentiometer wire of length 10 m has a total resistance of 20 Ω. It is connected in series with a 480 Ω external resistor and a stable 2.0 V battery of negligible internal resistance. What is the p…
  19. Why are standard resistance coils inside laboratory resistance boxes manufactured using alloys such as Manganin or Constantan rather than pure metals like copper?
  20. What is the equivalent resistance between two diametrically opposite points A and B on a uniform circular wire ring of total resistance R?
  21. How many identical 1.5 V dry cells, each having an internal resistance r = 0.5 Ω, must be connected in series to establish a current of 1.0 A through an external load resistance R = 10 Ω?
  22. In an electric circuit, a current of 5.0 A flows through a resistor for 2.0 minutes. How many electrons pass through any cross-section of the resistor during this time interval (e = 1.6 * 10^-19 C)?
  23. If the electric current flowing through an ohmic heating element is increased by 50 percent (I' = 1.5 I) while maintaining constant resistance, by what percentage does the rate of heat dissipation (el…
  24. Two resistors of and are connected in parallel. What is the equivalent resistance (in )?
  25. Two resistors of and are connected in parallel. What is the equivalent resistance (in )?
  26. Two resistors of and are connected in parallel. What is the equivalent resistance (in )?
  27. Two resistors of and are connected in parallel. What is the equivalent resistance (in )?
  28. Two resistors of and are connected in parallel. What is the equivalent resistance (in )?

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