Download App

Units and Measurements — Physics STD 11 Science — Question

Maharashtra BoardEnglish MediumSTD 11 SciencePhysicsUnits and Measurements3 Marks
Question
Explain how size of a planet or star is measured.
✓

Answer

  1. To determine the diameter (d) of a planet or star, two diametrically opposite points of the planet are viewed from the same observatory.
  2. If d is diameter of planet or star, angle subtended by it at any single point on the Earth is called angular diameter of planet.
  3. Let angle α be angle between these two directions.
  4. If distance between the Earth and planet or star (D) is known, $\alpha=\frac{ d }{ D }$
  5. This relation gives, d = α D
    Thus, diameter (d) of planet or star can be determined.

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "Answer the following in Brief" from Units and Measurements→Units and Measurements — all question types→Physics STD 11 Science question papers→Maharashtra Board STD 11 Science question papers→Maharashtra Board question paper generator→

Similar questions

A metallic of diameter $0.02 m$ contains $10$ free electrons per cubic metre. Find the drift velocity for free electrons, having an electric current of $100$ amperes flowing through the wire.
$($Given: charge on electron $= 1.6 \times 10^{-19}C)$
→
Distinguish between scalar product (dot product) and vector product (cross product).
→
Explain: Atoms are electrically neutral.
→
At what temperature will the speed of sound in air be $1.75$ times its speed at $N.T.P?$
→
A silver wire has a resistance of $4.2 \Omega $ at $27^\circ\ C$ and resistance $5.4 \Omega $ at $100^\circ\ C$. Determine the temperature coefficient of resistance.
→
What causes a larger current through a p-n junction diode when forward biased?
→
Find the colour code for the following value of resistor having tolerance ± 10%.
i. 330 Ω
ii. 100 Ω
iii. 47 kΩ
iv. 160 Ω
v. 1 kΩ
→
Two resistors $1 \Omega $ and $2 \Omega $ are connected in parallel combination.
i. Find equivalent resistance of parallel combination.
ii. When this parallel combination is connected to $9\ V$ supply, by neglecting internal resistance, calculate current through each resistor.
→
In real life objects, never travel with uniform velocity, even on a horizontal surface, unless something is done? Why
is it so? What is to be done?
→
The rate of flow of heat through a copper rod with temperature difference $30 ^{}\circ C$ is $1500$ cal/s. Find the thermal resistance of copper rod.
→