General Q&A for Class 12 · Page 164
5,215 free answers in General for Class 12 students, across CBSE, ICSE and State boards.
Question & Answer
Questions
- GeneralClass 12All
What is the mass of 45 kg?
The mass is 45 kilograms by definition. This is a straightforward statement - 45 kg is already a measurement of mass. On Earth, this mass would experience a weight of approximately 441 Newtons.
- GeneralClass 12All
What is a normal body mass in kg?
Normal body mass varies by height, age, and sex, but general ranges are: Adult women: 50-70 kg Adult men: 60-85 kg Children: Varies significantly with age A better indicator is Body Mass Index (BMI), which considers both height and weight. A healthy BMI falls between 18.5 and 24.9.
- GeneralClass 12All
Is 40kg heavy for a 12 year old?
40 kg is within the normal range for a 12-year-old, though it depends on height and build. According to growth charts: For 12-year-old girls: average is 40-45 kg For 12-year-old boys: average is 38-43 kg Individual variation is normal, and healthy weight depends more on overall health and development than a specific number.
- GeneralClass 12All
Is 100 grams one kg?
No, 100 grams is one-tenth of a kilogram (0.1 kg). You need 1,000 grams to equal one kilogram. This is a common misconception, but remember that the prefix "kilo-" means 1,000.
- GeneralClass 12All
How many 500g are in 3kg?
There are 6 units of 500g in 3 kg. Calculation: 3 kg = 3,000 g ÷ 500 g = 6
- GeneralClass 12All
How many 30 grams are in 1kg?
There are approximately 33.33 units of 30 grams in 1 kg. Calculation: 1,000 g ÷ 30 g = 33.33 This means you can fit 33 complete 30-gram portions in one kilogram.
- GeneralClass 12All
What is 1 stone in kg?
One stone equals 6.35 kilograms. The stone is a British imperial unit of mass still used in the UK and Ireland for measuring body weight. For example, 10 stone = 63.5 kg.
- GeneralClass 12All
What is the mass of a 5kg object?
The mass of a 5 kg object is simply 5 kilograms. This might seem like a circular answer, but it emphasizes that mass is an intrinsic property. Whether on Earth, the Moon, or in space, this object's mass remains 5 kg, though its weight would vary.
- GeneralClass 12All
Why do we calculate refractive index?
We calculate refractive index for numerous practical reasons: Material identification: Different substances have unique RI values Quality control: Verifying purity of liquids (honey, oils, beverages) Lens design: Engineering glasses, cameras, microscopes, telescopes Gemology: Identifying and valuing precious stones Medical diagnostics: Analyzing blood, ur
- GeneralClass 12All
Is refractive index only for light?
While most commonly applied to light (visible electromagnetic radiation), refractive index principles apply to all electromagnetic waves, including: Radio waves Microwaves Infrared radiation Ultraviolet radiation X-rays (though they behave differently) The concept can even extend to other wave phenomena like sound waves in some contexts, though the term "refractive index" is predominantly used for electrom
- GeneralClass 12All
What is the refractive index according to class 12th?
According to Class 12 physics curriculum, the refractive index is defined as: "The ratio of the speed of light in vacuum to the speed of light in the medium" Concepts covered include: Formula: n = c/v Snell's law: n₁ sin θ₁ = n₂ sin θ₂ Absolute and relative refractive index Laws of refraction Critical angle and total internal reflection Applications in lenses and optical instruments</
- GeneralClass 12All
How is sin to cos?
The relationship between sine and cosine is given by the complementary angle identity: sin θ = cos(90° - θ) cos θ = sin(90° - θ) Also, they're related by the Pythagorean identity: sin²θ + cos²θ = 1 To convert between them, you can use: cos θ = √(1 - sin²θ) or sin θ = √(1 - cos²θ)
- GeneralClass 12All
What are the two laws of refractive index?
The two fundamental laws of refraction (also called Snell's laws) are: First Law: The incident ray, the refracted ray, and the normal to the interface at the point of incidence all lie in the same plane. Second Law: For a given pair of media and for light of a given wavelength, the ratio of the sine of the angle of incidence to the sine of the angle of refraction is constant. This constant is the refractive index: sin i/sin r = n₂₁ (c
- GeneralClass 12All
What is the value of sin 720°?
Sin 720° = 0 Since sine has a period of 360°, sin 720° = sin(720° - 2×360°) = sin 0° = 0. Completing two full rotations brings you back to the starting position.
- GeneralClass 12All
What is sec 270° equal to?
Sec 270° is undefined because sec θ = 1/cos θ, and cos 270° = 0. Division by zero is undefined in mathematics.
- GeneralClass 12All
What is the exact value of sin 120 degrees?
Sin 120° = √3/2 (approximately 0.866) This can be found using the identity: sin 120° = sin(180° - 60°) = sin 60° = √3/2
- GeneralClass 12All
What is the square root of 720 simplified?
√720 = 12√5 Simplification: √720 = √(144 × 5) = √144 × √5 = 12√5 ≈ 26.83
- GeneralClass 12All
What is the value of cos 72 degrees in fraction?
Cos 72° = (√5 - 1)/4 (exact form) This equals approximately 0.309. This value comes from the geometry of a regular pentagon and involves the golden ratio.
- GeneralClass 12All
How do you measure mass?
Mass is measured using: Balance scales - Compare against known standard masses Electronic scales - Display mass digitally Triple-beam balances - Used in laboratories for precision Spring scales - Actually measure weight but display mass values Place the object on the scale and read the measurement directly in the desired unit (grams, kilograms, etc.).
- GeneralClass 12All
How to calculate body mass in kg?
To determine your body mass in kilograms: Use a calibrated scale set to kilogram units Weigh yourself in the morning before eating, wearing minimal clothing Read the displayed value directly - this is your mass in kg If your scale shows pounds, divide by 2.205 to convert to kilograms (1 kg = 2.205 lbs).