This physics problem tests your understanding of fundamental physical laws and their applications. The step-by-step solution below breaks down the problem using relevant equations and physical reasoning.
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You're on a roll — 3.1 Which terminal of the ammeter is represented by point P? Write down POSITIVE or NEGATIVE. Current flows from the positive terminal of the cell, through the external circuit, and back to the negative terminal. Ammeters are connected such that current enters the positive terminal and exits the negative terminal. Point P is on the side of the ammeter closer to the negative terminal of the cell, meaning current exits the ammeter at P. Therefore, P represents the NEGATIVE terminal. 3.2 Calculate the ammeter reading. Step 1: Calculate the equivalent resistance of the series combination of 4 \, and 2 \, . R_series = 4 \, + 2 \, = 6 \, Step 2: Calculate the total external resistance (R_ext) of the circuit. The 6 \, series combination is in parallel with the 3 \, resistor. (1)/(R_ext) = (1)/(6 \, ) + (1)/(3 \, ) (1)/(R_ext) = (1)/(6 \, ) + (2)/(6 \, ) = (3)/(6 \, ) R_ext = (6 \, )/(3) = 2 \, Step 3: Calculate the ammeter reading (I_total) using Ohm's law for the external circuit. The voltmeter reads the terminal voltage (V_ext) across the external resistance. I_total = V_extR_ext = (1.36 \, V)/(2 \, ) = 0.68 \, A The ammeter reading is 0.68 A. 3.3 Determine the internal resistance of the cell. Step 1: Use the formula for terminal voltage, V_ext = - I_totalr. 1.36 \, V = 1.5 \, V - (0.68 \, A)r Step 2: Rearrange the equation to solve for r. (0.68 \, A)r = 1.5 \, V - 1.36 \, V (0.68 \, A)r = 0.14 \, V r = (0.14 \, V)/(0.68 \, A) r ≈ 0.20588 \, The internal resistance of the cell is 0.21 . 3.4 An additional resistor X is connected parallel to the 3 \, resistor in the circuit. Will the reading on the ammeter INCREASE, DECREASE or REMAIN UNCHANGED? Give a reason for the answer. The reading on the ammeter will INCREASE. Reason: When an additional resistor is connected in parallel to the 3 \, resistor, the equivalent resistance of that parallel combination decreases. This leads to a decrease in the total external resistance (R_ext) of the circuit. Since the total resistance of the circuit (R_total = R_ext + r) decreases and the EMF () remains constant, the total current (I_total = ()/(R_total)) flowing through the circuit (and thus the ammeter reading) must increase. Drop the next question!