General Science - MCQ Practice Questions

Electric field at surface: E = kQ/r² = (9 × 10⁹ × 8 × 10⁻⁶)/(0.02)² = (72)/(4 × 10⁻⁴) = 1.8 × 10⁷ N/C.

Carnot efficiency: η = 1 - (T_cold/T_hot) = 1 - ($\frac{300}{400}$) = 1 - 0.75 = 0.25 = 25%. This is the theoretical maximum for any heat engine.

At critical angle θ_c, refracted ray becomes parallel to the interface. Beyond this angle, no refraction occurs; light completely reflects back into the denser medium (total internal reflection). This principle enables fiber optics.

Young's modulus is a material property independent of the wire's dimensions or elastic deformation state. It depends only on the material composition and atomic structure, not on physical changes.

Velocity is a vector quantity with both magnitude and direction, unlike speed which is scalar. Velocity can be negative, and in circular motion, velocity constantly changes direction.

Using v² = u² - 2gh, where final velocity v = 0, u = 20 m/s, g = 10 m/s². Therefore, 0 = 400 - 20h, giving h = 20 m.

Newton's Second Law: F = ma, where acceleration is directly proportional to force and inversely proportional to mass.

Using F = ma, F = 2 × 5 = 10 N. This is a direct application of Newton's Second Law.

Initial KE = ½m(v)² + ½m(2v)² = 2.5mv². Final velocity = 3v/2 (by momentum conservation). Final KE = ½(2m)(3v/2)² = 2.25mv²/4 = 0.84mv². Loss = 2.5 - 0.84 = 1.66, which is $\frac{2}{3}$ of initial KE.

When a block slides down a frictionless incline, gravity's component along the slope determines the acceleration.

Step 1: [Identify the Force Component Along the Incline]

On an incline, gravity acts vertically downward, but only its component parallel to the slope causes acceleration down the incline.

Step 2: [Apply Newton's Second Law]

Using F = ma, the net force along the incline equals mass times acceleration. The mass cancels out, giving us a pure kinematic result.

The acceleration down the incline is 4.9 m/s² (Answer: A)

Elastic PE = ½kx² = ½ × 100 × (0.1)² = ½ × 100 × 0.01 = 0.5 J.

Diffraction is the bending of waves around obstacles or through openings. This explains why we can hear sounds around corners.

Using Snell's Law: n₁sinθ₁ = n₂sinθ₂. 1 × sin(30°) = 1.5 × sinθ₂. 0.5 = 1.5sinθ₂. sinθ₂ = 0.333. θ₂ ≈ 19.47°.

The visible light spectrum ranges from violet (shortest wavelength ~400 nm) to red (longest wavelength ~700 nm). Red light has the longest wavelength among visible light.

Total resistance = 4 + 6 = 10Ω. Using Ohm's law: I = V/R = $\frac{10}{10}$ = 1 A.

A tungsten filament's resistance changes significantly with temperature during operation, making it non-ohmic. Metals at constant temperature follow Ohm's law.

The Weber (Wb) is the SI unit of magnetic flux, defined as Tesla × meter². 1 Wb = 1 T·m².

Using transformer equation: Vₛ/Vₚ = Nₛ/Nₚ. Vₛ = 220 × ($\frac{500}{100}$) = 220 × 5 = 1100 V.

An alpha particle is a helium-4 nucleus (₂He⁴) with 2 protons and 2 neutrons. Alpha decay decreases atomic number by 2 and mass number by 4. Alpha particles have low penetration power.

In beta-minus decay, a neutron converts to a proton, emitting an electron (beta particle) and an antineutrino. This increases atomic number by 1.