Measurement MCQs for NEET — Physics Questions with Answers

The unit of surface tension in the SI system is Newton per meter (N/m). Surface tension is defined as the force per unit length and thus has dimensions of force (Newton) divided by length (meter).

The unit of pascal-second (Pa·s) is used to measure the coefficient of viscosity. Viscosity is a measure of a fluid's resistance to flow, and the coefficient of viscosity quantifies this resistance. 1 Pascal-second is equivalent to 1 kg·m⁻¹·s⁻¹.

The unit of joule-second (Js) is used to measure Planck's constant. Planck's constant is a fundamental constant in physics that relates the energy of a photon to its frequency. It is denoted by the symbol \( h \) and its value is approximately \( 6.62607015 \times 10^{-34} \) Js.

Astronomical distances are vast and cannot be measured using direct methods like vernier callipers, spherometer, or screw gauge. Instead, indirect methods such as parallax, standard candles, and redshift measurements are used to determine these distances. These methods involve calculations and observations rather than direct measurement tools.

An electron microscope is used to measure dimensions of particles that are smaller than the wavelength of visible light, which is approximately 4000 Ã… (angstroms). Electron microscopes use a beam of electrons, which have much shorter wavelengths than visible light, allowing them to resolve much smaller details and measure extremely small particles.

$ \theta = 1.8 ^\circ = 0.01 \pi rad $ $ b = 1.27 \times 10 ^ 7 m $ $ D = { b \over \theta } = 4.06 \times 10^8 m $

To find the distance at which 4 AU subtends an angle of exactly 1" of arc, we can use the formula for angular size: \[ \theta = \frac{d}{D} \\] where \( \theta \) is the angular size in radians, \( d \) is the actual size, and \( D \) is the distance. Given \( d = 4 \times 1.496 \times 10^{11} \) m and \( \theta = 4.85 \times 10^{-6} \) rad: \[ D = \frac{4 \times 1.496 \times 10^{11}}{4.85 \times 10^{-6}} = 1.123 \times 10^{17} \text{ m} \\] So, the correct option is \( 1.123 \times 10^{17} \) m.

The percentage error is calculated using the formula: \[ \text{Percentage Error} = \left( \frac{\text{Absolute Error}}{\text{Measured Value}} \right) \times 100 \\] Given the distance is \( 100 \pm 5 \) cm: \[ \text{Percentage Error} = \left( \frac{5}{100} \right) \times 100 = 5\% \\] So, the correct option is \( 5\% \).