Ohm's Law in V-I Graphs

Steps:

• Plot voltage (V) on y-axis and current (I) on x-axis for the wire.
• The graph is a straight line for a metal wire, an ohmic conductor.
• Gradient equals change in V divided by change in I (ΔV/ΔI).
• From Ohm's law (V = IR), rearrange to R = V/I, so gradient represents resistance R.

Why D is correct:

• Ohm's law states V = IR; thus, the slope ΔV/ΔI directly gives resistance R.

Why the others are wrong:

• A: Charge Q = I × t (time), unrelated to graph slope.
• B: Emf is the battery's potential difference, a fixed value, not the slope.
• C: Energy E = V × I × t (power × time), not represented by slope.

Final answer: D