The given graph shows the relationship between the potential difference (V) across theterminals of the cell and the current (I) drawn from the cell.The electromotive force (E) and the internal resistance (r) of the cell are
Correct answer: B. E = 0.4 V and r = 2 Ω.
- A. E = 2 V and r = 0.4 Ω.
- B. E = 0.4 V and r = 2 Ω.
- C. E = 0.5 V and r = 0.4 Ω.
- D. E = 0 V and r = 2.5 Ω.
Explanation
The correct answer is Option B:E = 0.4 V and r = 2 Ω.. In a V-I graph, the y-intercept represents the electromotive force (E) of the cell, and the negative slope of the line is indicative of the internal resistance (r). The graph shows E = 0.4 V as the y-intercept and demonstrates a slope that corresponds to an internal resistance of 2 Ω. Other options either miscalculate the y-intercept or the slope, leading to incorrect values for E and r.
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About Internal Resistance of Sources
Internal resistance is the opposition to current inside a cell or other source, causing terminal voltage to fall below its emf when current flows. Questions use E = V + Ir, current in complete circuits, lost volts, source combinations, and the difference between internal resistance and the external load resistance.
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