Pregunta
1. Before being connected in a circuit, the emf of a certain dry cell is measured and found to be 4.5 V . When it is connected to the circuit, it supplies a current of 0.75 A , but the voltage reading across the dry cells terminals read 4.25 V . Using this information determine; (a) The voltage drop across the dry cells (b) The internal resistance of the dry cell when it is supplying current in this circuit.
Ask by Nguyen Barnett. in Papua New Guinea
Feb 28,2025
Solución de inteligencia artificial de Upstudy
Respuesta verificada por el tutor
Responder
(a) The voltage drop across the dry cell is 0.25 V.
(b) The internal resistance of the dry cell is approximately 0.33 Ω.
Solución
Given:
• No-load emf (E) = 4.5 V
• When connected, current (I) = 0.75 A
• Terminal voltage (V_terminal) = 4.25 V
Step 1. Determine the voltage drop (V_drop) across the internal resistance:
V_drop = E − V_terminal = 4.5 V − 4.25 V = 0.25 V
Step 2. Determine the internal resistance (r) using Ohm’s Law:
r = V_drop / I = 0.25 V / 0.75 A ≈ 0.33 Ω
Final Answers:
(a) The voltage drop across the dry cell is 0.25 V.
(b) The internal resistance of the dry cell is approximately 0.33 ohms.
Respondido por UpStudy AI y revisado por un tutor profesional
Como
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Extra Insights
The voltage drop across the dry cell can be calculated by finding the difference between the emf and the terminal voltage. So, it's 4.5 V - 4.25 V = 0.25 V. To find the internal resistance of the dry cell, we use Ohm's Law (V = IR). Rearranging gives us resistance (r) = V/I. The internal resistance, therefore, is 0.25 V / 0.75 A = 0.33 ohms. Now you know the voltage drop is 0.25 V and the internal resistance is about 0.33 ohms!
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