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UPCET / UPSEE Current Electricity — practice questions — page 3

Explore 102 free Current Electricity questions in UPCET / UPSEE Physics. Open each question or exercise to read its content, reference answers and available explanation.

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Current Electricity questions and exercises with answers

Showing questions 61–90 of 102.

In a metallic wire of fixed n and area A, if the current is doubled, the electron drift speed:Read the answer and worked solution →A wire is stretched to twice its original length while keeping its volume constant. Its new resistance is:Read the answer and worked solution →Two bulbs rated 100 W and 60 W are designed for the same supply voltage. Compared with the 60 W bulb, the 100 W bulb has:Read the answer and worked solution →A platinum resistance thermometer reads 5.00 Ω at 0°C and 5.23 Ω at 100°C. When its resistance is 5.795 Ω, the temperature is about:Read the answer and worked solution →The heat produced in a 5 Ω resistor carrying a steady current of 2 A for 10 s is:Read the answer and worked solution →Estimate the drift speed of electrons in a copper wire carrying 1.5 A with cross-section 1.0×10⁻⁷ m² and n = 8.5×10²⁸ m⁻³ (e = 1.6×10⁻¹⁹ C):Read the answer and worked solution →Two cells, each of emf 1.5 V and internal resistance 0.5 Ω, are connected in series across a 2 Ω resistor. The current through the resistor is:Read the answer and worked solution →Two identical cells, each of emf 1.5 V and internal resistance 0.5 Ω, are connected in parallel across a 1 Ω resistor. The current through the resistor is:Read the answer and worked solution →The maximum current that can be drawn from a cell of emf 1.5 V and internal resistance 0.3 Ω is:Read the answer and worked solution →A Wheatstone bridge is balanced with arms P = 10 Ω, Q = 20 Ω and R = 15 Ω. The unknown resistance S is:Read the answer and worked solution →A 3 Ω resistor is connected in series with a parallel combination of a 6 Ω and a 3 Ω resistor. The equivalent resistance of the network is:Read the answer and worked solution →Sort Kirchhoff's rules by their lawRead the answer and worked solution →Pick the bridge facts, fastRead the answer and worked solution →Complete the bridge storyRead the answer and worked solution →Knock out the bridge mythsRead the answer and worked solution →Flip and match the circuit toolsRead the answer and worked solution →True or false: what emf actually isRead the answer and worked solution →Complete the statement of Ohm's lawRead the answer and worked solution →Tap every way Ohm's law can failRead the answer and worked solution →Match each device or material to its behaviourRead the answer and worked solution →Sort each material by its resistivityRead the answer and worked solution →Complete the resistance relationRead the answer and worked solution →True or false: resistance and resistivityRead the answer and worked solution →Match each of Kirchhoff's rules to what it conservesRead the answer and worked solution →Kirchhoff's rulesRead the answer and worked solution →Order the steps: find an unknown resistance with a Wheatstone bridgeRead the answer and worked solution →True or false: internal resistanceRead the answer and worked solution →Which quantity is which?Read the answer and worked solution →Assertion and reasonRead the answer and worked solution →Charge carriersRead the answer and worked solution →

Worked practice questions

In a metallic wire of fixed n and area A, if the current is doubled, the electron drift speed:

  1. is halved
  2. remains unchanged
  3. becomes four times
  4. doubles
Show answer and solution

Correct answer: D. doubles

Since I = neAv_d, with n and A fixed v_d ∝ I, so doubling the current doubles the drift speed.

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A wire is stretched to twice its original length while keeping its volume constant. Its new resistance is:

  1. 4 times the original
  2. 2 times the original
  3. unchanged
  4. half the original
Show answer and solution

Correct answer: A. 4 times the original

Volume is constant, so doubling the length halves the area. R = ρl/A scales as l/A → (2)/(½) = 4 times the original.

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Two bulbs rated 100 W and 60 W are designed for the same supply voltage. Compared with the 60 W bulb, the 100 W bulb has:

  1. a higher resistance
  2. zero resistance
  3. the same resistance
  4. a lower resistance
Show answer and solution

Correct answer: D. a lower resistance

At a fixed voltage P = V²/R, so the higher-power (100 W) bulb must have the lower resistance.

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