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QUESTIONS ON CURRENT ELECTRICITY
SOUND WAVE
- What is the frequency of a wave if its period is 0.05 seconds?
- A) 10 Hz
- B) 20 Hz
- C) 25 Hz
- D) 50 Hz
Answer: B) 20 Hz
- Which of the following is not a characteristic of waves?
- A) Reflection
- B) Refraction
- C) Inertia
- D) Diffraction
Answer: C) Inertia
- What type of wave oscillates perpendicular to the direction of energy transfer?
- A) Longitudinal wave
- B) Transverse wave
- C) Surface wave
- D) Electromagnetic wave
Answer: B) Transverse wave
- The speed of a wave is determined by which of the following?
- A) Amplitude
- B) Wavelength and frequency
- C) Frequency and phase
- D) Wavelength and time period
Answer: B) Wavelength and frequency
- The equation of a progressive wave is given by ( y = A \sin(kx – \omega t) ). What does ( A ) represent?
- A) Wavelength
- B) Amplitude
- C) Frequency
- D) Wave speed
Answer: B) Amplitude
- In the wave equation ( y = A \sin(kx – \omega t) ), ( k ) is known as:
- A) Angular frequency
- B) Wave number
- C) Phase constant
- D) Amplitude
Answer: B) Wave number
- The relationship between speed ( v ), frequency ( f ), and wavelength ( \lambda ) is given by:
- A) ( v = f + \lambda )
- B) ( v = f \cdot \lambda )
- C) ( v = \frac{f}{\lambda} )
- D) ( v = f – \lambda )
Answer: B) ( v = f \cdot \lambda )
- Which type of wave requires a medium to propagate?
- A) Electromagnetic wave
- B) Sound wave
- C) Light wave
- D) All of the above
Answer: B) Sound wave
- What is the speed of sound in air at room temperature (20°C)?
- A) 343 m/s
- B) 300 m/s
- C) 1500 m/s
- D) 400 m/s
Answer: A) 343 m/s
- The phenomenon of sound bending around obstacles is called:
- A) Reflection
- B) Refraction
- C) Diffraction
- D) Absorption
Answer: C) Diffraction
- Which of the following frequencies is considered to be ultrasonic?
- A) 20 Hz
- B) 1000 Hz
- C) 20 kHz
- D) 50 kHz
Answer: C) 20 kHz
- The human audible range of sound frequencies is typically:
- A) 10 Hz to 20 kHz
- B) 20 Hz to 20 kHz
- C) 100 Hz to 10 kHz
- D) 1 Hz to 100 kHz
Answer: B) 20 Hz to 20 kHz
- What is the primary function of a convex lens?
- A) Diverge light rays
- B) Converge light rays
- C) Reflect light rays
- D) Absorb light rays
Answer: B) Converge light rays
- In a plane mirror, the image formed is:
- A) Real and inverted
- B) Virtual and upright
- C) Both real and virtual
- D) Always enlarged
Answer: B) Virtual and upright
- Which optical instrument is used to magnify small objects?
- A) Microscope
- B) Telescope
- C) Periscope
- D) Spectrometer
Answer: A) Microscope
- What type of lens is used in a projector?
- A) Concave lens
- B) Convex lens
- C) Cylindrical lens
- D) Plano-convex lens
Answer: B) Convex lens
- The critical angle for total internal reflection occurs when:
- A) The angle of incidence is greater than the angle of refraction
- B) The angle of incidence equals the angle of refraction
- C) The angle of incidence is equal to the critical angle
- D) Light travels from a medium of lower refractive index to higher refractive index
Answer: C) The angle of incidence is equal to the critical angle
- Which law describes the relationship between the angles of incidence and refraction?
- A) Snell’s Law
- B) Newton’s Law
- C) Hooke’s Law
- D) Ohm’s Law
Answer: A) Snell’s Law
- What happens to the wavelength of light when it passes from air into water?
- A) Increases
- B) Decreases
- C) Remains the same
- D) Becomes zero
Answer: B) Decreases
- The focal length of a concave lens is:
- A) Positive
- B) Negative
- C) Zero
- D) Infinity
Answer: B) Negative
- Which optical instrument uses mirrors to gather and focus light from distant objects?
- A) Microscope
- B) Camera
- C) Telescope
- D) Spectrometer
Answer: C) Telescope
- A lens that can magnify an object by bending light rays is called:
- A) Convex lens
- B) Concave lens
- C) Cylindrical lens
- D) Flat lens
Answer: A) Convex lens
- What is the power of a lens with a focal length of 0.5 m?
- A) +2 D
- B) +0.5 D
- C) -2 D
- D) -0.5 D
Answer: A) +2 D
- Which optical effect is responsible for the rainbow?
- A) Reflection
- B) Refraction
- C) Diffraction
- D) Dispersion
Answer: D) Dispersion
- What is the unit of electric charge?
- A) Volt
- B) Ampere
- C) Coulomb
- D) Ohm
Answer: C) Coulomb
- Which of the following materials is a good insulator?
- A) Copper
- B) Silver
- C) Rubber
- D) Aluminum
Answer: C) Rubber
- Coulomb’s law states that the force between two charges is:
- A) Directly proportional to the product of the charges
- B) Inversely proportional to the square of the distance between them
- C) Both A and B
- D) Independent of the medium
Answer: C) Both A and B
- The electric field due to a point charge decreases with distance as:
- A) ( \frac{1}{r} )
- B) ( \frac{1}{r^2} )
- C) ( r^2 )
- D) ( r )
Answer: B) ( \frac{1}{r^2} )
- The concept of electric potential is related to:
- A) The work done per unit charge
- B) The current through a conductor
- C) The resistance of a circuit
- D) The capacitance of a capacitor
Answer: A) The work done per unit charge
- What happens to the capacitance of a capacitor if the distance between the plates is increased?
- A) Increases
- B) Decreases
- C) Remains the same
- D) Becomes zero
Answer: B) Decreases
- What is the unit of resistance?
- A) Watt
- B) Ohm
- C) Volt
- D) Ampere
Answer: B) Ohm
- Ohm’s Law states that the current through a conductor is:
- A) Directly proportional to voltage and inversely proportional to resistance
- B) Directly proportional to resistance
- C) Inversely proportional to voltage
- D) Constant regardless of voltage
Answer: A) Directly proportional to voltage and inversely proportional to resistance
- In a series circuit, the total resistance is:
- A) The sum of individual resistances
- B) The product of individual resistances
- C) Equal to the highest resistance
- D) Constant
Answer: A) The sum of individual resistances
- What does a voltmeter measure?
- A) Current
- B) Voltage
- C) Resistance
- D) Power
Answer: B) Voltage
- In an AC circuit, the voltage varies with time in a:
- A) Linear fashion
- B) Constant fashion
- C) Sinusoidal fashion
- D) Exponential fashion
Answer: C) Sinusoidal fashion
- What is the RMS value of an AC current of peak value ( I_0 )?
- A) ( I_0 )
- B) ( \frac{I_0}{\sqrt{2}} )
- C) ( \sqrt{2} I_0 )
- D) ( 2I_0 )
Answer: B) ( \frac{I_0}{\sqrt{2}} )
- In an AC circuit, what component stores energy in an electric field?
- A) Resistor
- B) Inductor
- C) Capacitor
- D) Transformer
Answer: C) Capacitor
- What is the phase difference between voltage and current in a purely resistive AC circuit?
- A) 0 degrees
- B) 90 degrees
- C) 180 degrees
- D) 270 degrees
Answer: A) 0 degrees
- Which of the following is one of Maxwell’s equations?
- A) ( \nabla \cdot \mathbf{E} = 0 )
- B) ( \nabla \cdot \mathbf{B} = 0 )
- C) ( \nabla \times \mathbf{E} = -\frac{\partial \mathbf{B}}{\partial t} )
- D) All of the above
Answer: D) All of the above
- The unit of magnetic flux is:
- A) Weber
- B) Tesla
- C) Ampere
- D) Henry
Answer: A) Weber
- The right-hand rule is used to determine the direction of:
- A) Current flow
- B) Magnetic field lines
- C) Force on a charged particle
- D) All of the above
Answer: D) All of the above
- A changing magnetic field induces an electric field according to:
- A) Faraday’s Law of Electromagnetic Induction
- B) Ohm’s Law
- C) Kirchhoff’s Law
- D) Coulomb’s Law
Answer: A) Faraday’s Law of Electromagnetic Induction
- Which of the following best describes sound waves?
- A) Electromagnetic waves
- B) Longitudinal mechanical waves
- C) Transverse waves
- D) Surface waves
Answer: B) Longitudinal mechanical waves
- What principle do optical instruments like cameras and microscopes primarily use?
- A) Reflection only
- B) Refraction only
- C) Both reflection and refraction
- D) Diffraction only
Answer: C) Both reflection and refraction
- The phenomenon of light splitting into different colors when passing through a prism is called:
- A) Reflection
- B) Dispersion
- C) Refraction
- D) Diffraction
Answer: B) Dispersion
- Which of the following describes the intensity of a sound wave?
- A) The speed of sound
- B) The amplitude of the wave
- C) The frequency of the wave
- D) The wavelength of the wave
Answer: B) The amplitude of the wave
- What is the primary cause of the Doppler effect in sound?
- A) Change in temperature
- B) Relative motion between the source and observer
- C) Change in frequency
- D) Variation in medium density
Answer: B) Relative motion between the source and observer
- In an electric circuit, what does a diode do?
- A) Increases current
- B) Decreases voltage
- C) Allows current to flow in one direction only
- D) Stores charge
Answer: C) Allows current to flow in one direction only
- The formula for electric power in a circuit is given by:
- A) ( P = VI )
- B) ( P = I^2R )
- C) ( P = \frac{V^2}{R} )
- D) All of the above
Answer: D) All of the above
- What type of wave is used in communication technologies like radios?
- A) Longitudinal wave
- B) Electromagnetic wave
- C) Transverse wave
- D) Surface wave
Answer: B) Electromagnetic wave