Exams › JEE Main › General

In an experiment to measure focal length (f) of convex lens, the least counts of the measuring scales for the position of object (u) and for the position of image (v) are Δ u and Δ v, respectively. The error in the measurement of the focal length of the convex lens will be :

1. v v u u Δ + Δ
2. ⎥ ⎦ ⎤ ⎢ ⎣ ⎡ Δ + Δ 2 2 2 v v u u f
3. ⎥ ⎦ ⎤ ⎢ ⎣ ⎡ Δ + Δ v v u u f 2
4. ⎥ ⎦ ⎤ ⎢ ⎣ ⎡ Δ + Δ v v u u f

Correct answer: ⎥ ⎦ ⎤ ⎢ ⎣ ⎡ Δ + Δ 2 2 2 v v u u f

Related JEE Main General questions

• A charge Q is uniformly distributed over a long rod AB of length L as shown in the figure. The electric potential at the point O lying at a distance L from the end A is - L A O L B
• A sonometer wire of length 1.5 m is made of steel. The tension in it produces an elastic strain of 1%. What is the fundamental frequency of steel if density and elasticity of steel are 7.7 × 10 3 kg/m 3 and 2.2 × 10 11 N/m 2 respectively ?
• A projectile is given an initial velocity of ) j ˆ 2 i ˆ ( + m/s, where i ˆ is along the ground and j ˆ is along the vertical. If g = 10 m/s 2 , the equation of its trajectory is -
• A uniform cylinder of length L and mass M having cross-sectional area A is suspended, with its length vertical, from a fixed point by a massless spring, such that it is half submerged in a liquid of density σ at equilibrium position. The extension x 0 of the spring when it is in equilibrium is - (Here k is spring constant)
• The graph between angle of deviation ( δ ) and angle of incidence (i) for a triangular prism is represented by -
• Diameter of a plano-convex lens is 6 cm and thickness at the centre is 3 mm. If speed of light in material of lens is 2 × 10 8 m/s, the focal length of the lens is -

⚔️ Practice JEE Main General free + battle 1v1 →