Let mathbfu and mathbfv be the distances of the object and the image from a lens of focal length f . The correct graphical representation of mathbfu and mathbfv for a convex lens when |mathbfu| > f , is

Solution & Explanation

### Related Formula (u - f)(v - f) = f^2 > **Note:** Expanding (u - f)(v - f) = f^2 yields uv - f(u + v) = 0, which simplifies directly to the magnitude form of the lens formula frac1v + frac1u = frac1f. --- ### Core Logic #### 1. Lens Formula and Sign Conventions For a convex lens forming a real image (|u| > f): * **Object distance (u):** Negative (-u) * **Image distance (v):** Positive (+v) * **Focal length (f):** Positive (+f) Substituting these into the standard lens formula frac1v - frac1u = frac1f: frac1v - left(-frac1uright) = frac1f frac1v + frac1u = frac1f --- #### 2. Analyzing Graphical Behavior ##### **A. The v vs. u Graph** Rearranging the equation for v: frac1v = frac1f - frac1u = fracu - fuf implies v = fracufu - f * **When u to f:** v to infty (Vertical asymptote at u = f) * **When u to infty:** v to f (Horizontal asymptote at v = f) * **When u = 2f:** v = 2f This relationship represents a **rectangular hyperbola** when plotting magnitudes (or in the respective coordinate quadrants under Cartesian sign conventions). ##### **B. The frac1v vs. frac1u Graph** Plotting the reciprocals (frac1v on the y-axis and frac1u on the x-axis): frac1v = -frac1u + frac1f This matches the straight-line equation y = mx + c: * **Slope (m):** -1 * **Intercept (c):** frac1f --- ### Chapter Mix Class 12 Physics: Ray Optics and Optical Instruments
Lens formula explanation curves
Lens formula explanation curves

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Q34 jee_main_2024_31_jan_morning Prism Deviation
The refractive index of a prism with apex angle A is cot(A/2). The angle of minimum deviation is :
  • A. delta_mathrmm = 180^circ - A
  • B. delta_mathrmm = 180^circ - 3A
  • C. delta_mathrmm = 180^circ - 4A
  • D. delta_mathrmm = 180^circ - 2A

Solution

### Related Formula mu = fracsinleft(fracA + delta_m2right)sinleft(fracA2right) ### Core Logic Given that the refractive index mu = cotleft(fracA2right). Substituting this into the prism formula: cotleft(fracA2right) = fracsinleft(fracA + delta_m2right)sinleft(fracA2right) fraccosleft(fracA2right)sinleft(fracA2right) = fracsinleft(fracA + delta_m2right)sinleft(fracA2right) Equating the numerators: cosleft(fracA2right) = sinleft(fracA + delta_m2right) We can rewrite cosine in terms of sine: sinleft(fracpi2 - fracA2right) = sinleft(fracA + delta_m2right) ### Step 2: Solve for Deviation Comparing the angles inside the sine functions: fracpi2 - fracA2 = fracA2 + fracdelta_m2 Multiply the entire equation by 2: pi - A = A + delta_m delta_m = pi - 2A Converting radians to degrees: delta_m = 180^circ - 2A ### Pattern Recognition Whenever refractive index mu = cot(A/2), the relation sin(90^circ - A/2) strictly matches the prism sine equation, meaning minimum deviation delta_m is always 180^circ - 2A. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Physics: Ray Optics And Optical Instruments

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