General Q&A for Class 12 · Page 172
5,215 free answers in General for Class 12 students, across CBSE, ICSE and State boards.
Question & Answer
Questions
- GeneralClass 12All
How to calculate eMF equation?
The EMF (electromotive force) equation depends on context: For AC generators: EMF = N × B × A × ω × sin(ωt) N = number of turns B = magnetic field strength A = coil area ω = angular frequency (ω = 2πf) For changing magnetic flux: EMF = -N(dΦ/dt) This is Faraday's Law of electromagnetic induction The frequen
- GeneralClass 12All
How do you calculate average speed over distance?
Average speed over a distance is calculated by dividing the total distance by the total time taken to cover that distance. The formula remains: Average Speed = Distance ÷ Time. Ensure you account for all portions of the journey when calculating total time.
- GeneralClass 12All
How do you calculate average speed with curves?
When traveling along a curved path, average speed is still total distance traveled (measured along the curve) divided by total time. The curvature affects the actual path distance but doesn't change the formula. Measure the actual path length along the curve, not the straight-line distance.
- GeneralClass 12All
Why is average speed calculated?
Average speed is calculated to: Estimate travel time for trips Compare efficiency of different routes or vehicles Analyze performance in sports and racing Plan schedules and logistics Understand overall journey characteristics despite speed variations Calculate fuel consumption and costs
- GeneralClass 12All
Which average is suitable to find the average speed in the 4 × 100 relay race?
For a relay race where each runner covers equal distance (100m each), use the harmonic mean if you know individual speeds, or calculate total distance (400m) divided by total time. Since relay races measure total time directly, the simplest method is 400 meters ÷ total team time.
- GeneralClass 12All
How to calculate average per hour?
"Average per hour" typically refers to average speed in units per hour (km/h, mph, etc.). Calculate by dividing the total quantity (distance, production, etc.) by the total number of hours. For speed: Distance ÷ Hours = Average speed per hour.
- GeneralClass 12All
What is the average speed of a car in km/h?
This depends on the specific journey. A typical car might average 30-50 km/h in city driving, 60-90 km/h on country roads, and 100-120 km/h on highways. To find it for a specific trip, divide total kilometers traveled by total hours taken.
- GeneralClass 12All
What is frequency in physics?
Frequency is the number of complete oscillations, cycles, or waves that occur in one second. In physics, it measures how often a repeating event happens per unit of time. For example, if a pendulum swings back and forth 5 times in one second, its frequency is 5 Hz. Frequency applies to sound waves, electromagnetic waves, vibrations, and any periodic motion.
- GeneralClass 12All
What is the unit of frequency?
The standard unit of frequency is Hertz (Hz), named after physicist Heinrich Hertz. One Hertz equals one cycle per second. Larger units include kilohertz (kHz = 1,000 Hz), megahertz (MHz = 1,000,000 Hz), and gigahertz (GHz = 1,000,000,000 Hz). These units help express different frequency ranges more conveniently.
- GeneralClass 12All
Is Hz a unit of frequency?
Yes, Hz (Hertz) is the SI unit for measuring frequency. When you see a measurement in Hz, it tells you how many complete cycles happen each second. For instance, 60 Hz means 60 cycles per second, commonly used for electrical power in many countries.
- GeneralClass 12All
What is the frequency of 20m?
If 20m refers to wavelength, you can calculate frequency using f = v/λ: For electromagnetic waves (radio waves in air/vacuum): f = (3 × 10⁸ m/s) ÷ 20m = 15,000,000 Hz = 15 MHz This is in the shortwave radio band For sound waves (in air at 20°C): f = 343 m/s ÷ 20m = 15 Hz This is a very low frequency, below typical human hearing
- GeneralClass 12All
What is 1 MHz equal to?
1 MHz (megahertz) equals: 1,000,000 Hz (one million Hertz) 1,000 kHz (one thousand kilohertz) 001 GHz (one-thousandth of a gigahertz) MHz is commonly used for radio frequencies, processor speeds, and other applications where thousands of cycles per second occur.
- GeneralClass 12All
How to calculate frequency in MHz?
To convert frequency to MHz: From Hz: Divide by 1,000,000 (MHz = Hz ÷ 1,000,000) Example: 5,000,000 Hz = 5 MHz From kHz: Divide by 1,000 (MHz = kHz ÷ 1,000) Example: 2,500 kHz = 2.5 MHz From GHz: Multiply by 1,000 (MHz = GHz × 1,000) Example: 2.4 GHz = 2,400 MHz
- GeneralClass 12All
How to convert Hz to frequency?
Hz (Hertz) already is frequency—it doesn't need conversion. However, you might want to: Convert between units: Hz to kHz (÷1,000), Hz to MHz (÷1,000,000) Calculate from period: f (Hz) = 1/T (seconds) Determine from wavelength: f (Hz) = v (m/s) ÷ λ (m) If you have a value in Hz, you already have the frequency.
- GeneralClass 12All
How to convert 50Hz to 60Hz?
You cannot directly "convert" 50 Hz to 60 Hz—these are different operating frequencies. However, you can convert power systems using: Frequency converters: Electronic devices that change AC frequency Motor-generator sets: Motor runs on 50 Hz, generator produces 60 Hz Variable frequency drives (VFDs): Control motor speeds regardless of input frequency This is necessary when using 60 Hz e
- GeneralClass 12All
What is wave frequency?
Wave frequency is the number of complete wave cycles that pass a fixed point per second. For any wave sound, light, water, or electromagnetic frequency determines key properties: Sound waves: Frequency determines pitch (high frequency = high pitch) Light waves: Frequency determines color (violet highest, red lowest in visible spectrum) Radio waves: Frequency determines the broadcast channel H
- GeneralClass 12All
How to find signal frequency?
To determine signal frequency: Oscilloscope method: Measure the period (T) of one complete cycle on screen, then calculate f = 1/T Frequency counter: Connect the signal directly; the device displays frequency Spectrum analyzer: Shows frequency content of complex signals Software analysis: Use programs like Audacity, MATLAB, or Python libraries for digital signals
- GeneralClass 12All
What are the two types of frequencies?
The two main frequency classifications are: Natural (fundamental) frequency: The inherent frequency at which a system oscillates when disturbed (like a guitar string's primary vibration) Forced frequency: The frequency imposed on a system by an external force Alternatively, frequencies can be categorized as: Audio frequencies (20 Hz - 20 kHz): Sound we can hear Radio fr
- GeneralClass 12All
How to calculate frequency in electrical?
For electrical systems, frequency is calculated as: f = 1/T, where T is the period of one complete AC cycle For a standard electrical grid: 50 Hz systems: T = 1/50 = 0.02 seconds per cycle 60 Hz systems: T = 1/60 ≈ 0.0167 seconds per cycle You can also measure using power quality analyzers or oscilloscopes connected to the circuit (with proper safety precautions).
- GeneralClass 12All
Which is greater, 20 Hz or 20,000 Hz?
20,000 Hz is greater than 20 Hz it's 1,000 times larger. This comparison represents the extremes of human hearing: 20 Hz: Very low bass, felt as much as heard (like a subwoofer) 20,000 Hz: Upper limit of hearing, very high treble (like a whistle) Higher frequency means more cycles per second, higher energy, and shorter wavelength.