<h2>
Answer: B) It would be best to use a concave mirror, with the object to be ignited positioned halfway between the mirror and its center of curvature. </h2>
Explanation:
To start a fire it is more optimal to use a concave mirror than a plane mirror. This is because the concave mirror allows concentrating sunlight at a point (the focal point) on an object that acts as fuel and ignite the fire there.
For this it is necessary the object to be positioned between the center of curvature of the mirror and the mirror (its focus). Thus the rays of the Sun, when converging on the focus, will heat the object and make it burn.
Hence, the correct option is B.
Answer:
Diaphragm or Iris: Many microscopes have a rotating disk under the stage. This diaphragm has different sized holes and is used to vary the intensity and size of the cone of light that is projected upward into the slide.
Explanation:
Answer: D.) 3hrs
Explanation:
Given the following :
A boat can move at a constant velocity of 8 km/h; How long will it take for the boat to move 24 km
Recall:
Velocity = Displacement / time
For the boat to travel a distance of 24 km at a constant velocity of 8km /hr
Time taken = Displacement(distance moved) / velocity
Time taken = 24km / 8kmhr^-1
Tine taken = 3hrs
Answer:
Explanation:
The problem is based on the concept of Doppler's effect of em wave .
Expression for apparent frequency can be given as follows
n = N x (V - v ) / ( V + v )
n is apparent frequency , N is real frequency , V is velocity of light and v is velocity of cloud.
n = 6 x 10⁹ ( 3 x 10⁸ - 8.52 ) / ( 3 x 10⁸ + 8.52 )
= 6 x 10⁹ ( 3 x 10⁸ ) ( 3 x 10⁸ + 8.52 )⁻¹
= 6 x 10⁹ ( 3 x 10⁸ ) ( 3 x 10⁸)⁻¹ ( 1 + 8.52/3 x 10⁸ )⁻¹
= 6 x 10⁹ ( 1 - 8.52/3 x 10⁸ )
= 6 x 10⁹ - 6 x 10⁹x 8.52/ (3 x 10⁸ )
= 6 x 10⁹ 1 - 170 .
So change in frequency = 170 approx.
C. Space.
Radiation is a process by which heat energy is transferred through space.
