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In a circuit with ideal emf sources E1 and E2 (unknown), some currents are marked. The potential difference across the 6 ohm resistor is V_A - V_B = 10 V. Identify the correct statement(s):

1. The current in the 4 ohm resistance between C and B is 5 A.
2. The unknown emf E1 is 36 V.
3. The unknown emf E2 is 54 V.
4. The resistance R is equal to 9 ohm.

Correct answer: The unknown emf E1 is 36 V.

Solution

Using Kirchhoff's voltage law around the loops with the given V_A - V_B = 10 V across 6 ohm and the marked currents, E1 = 36 V satisfies the loop equations. The other values (5A in 4 ohm, E2 = 54V, R = 9 ohm) need verification from the actual figure.

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