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In an unbiased n-p junction electrons diffuse from n-region to p-region because

Asked in JEE Main Online 2015 · Diffusion and drift currents

• (1) holes in p-region attract them
• (2) electrons travel across the junction due to potential difference
• (3) electron concentration in n-region is more as compared to that in p-region
• (4) only electrons move from n to p region and not the vice-versa.

Step-by-step solution

Why the other options are wrong

• (1) Diffusion is driven by a concentration gradient, not attraction.
• (2) The junction potential actually opposes this flow; it drives drift, not diffusion.
• (4) Holes diffuse from p to n at the same time.

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