A-LevelPhysicsGravitational fields9702/42 · Feb/Mar 2019 · Q47 Marks
State three features of the orbit of a geostationary satellite.
- (a)State three features of the orbit of a geostationary satellite.[3]
- (b)A signal is transmitted from Earth to a geostationary satellite. Initially, the signal has power 3.2kW. The signal is attenuated by 194 dB. Calculate the signal power received by the satellite.[2]
- (c)Suggest one advantage and one disadvantage of the use of geostationary satellites compared with polar-orbiting satellites for communication between points on the Earth's surface.[2]
Mark scheme
Marking points from the official mark scheme (Feb/Mar 2019). The mark or mark type is shown in brackets.
- [B3] Any three from: above the Equator; period 24 hours; orbits west to east; one particular orbital radius
- [C1] attenuation = 10 lg(P₁ / P₂); 194 = 10 lg (3.2 × 10³ / P₂)
- [A1] P₂ = 1.3 x 10⁻¹⁶ W
- [B1] advantage: e.g. no tracking required
- [B1] disadvantage: e.g. longer time delay
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