3 questions..please help (1 Viewer)

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hey guys,
i'm coming up with more questions..its just that now, during the holidays i cannot ask the teachers...so i hope u can understand and thanks for helping out!

 

[rama_v]

11. just use E = hf = hc/l where l is wavelength

so E = (6.626 x 10^-34)(3x10⁸) / (20 x 10^-9)

 

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ahh yes..thatz right. thanks!

but man! the other two pictures arent showing up...let me try again

 

[rama_v]

For the second one its clear from the graph that the spacecraft would want to send signals that can have the best possibility of travelling through the atmosphere and down to the ground where the signals can be picked up by a large satellite dish. What you need to do is convert the MHz to Wavelength. Again use the formula c = fl where l is wavelength. Rearranging, you get:

Wavelength = c / f = (3 x 10⁸) / (2295 x 10⁶) because the frequency is in MegaHertz (need to convert to Hertz).

therefore wavelength = 1.31 x 10^-1 m

When looking at the graph, we can see that the transmission of this frequency (i.e. wavelength) is very high (about 95%), so it would be suitable for use as there is a great possibility that the signals will reach earth.

Im pretty sure the first one is not part of the sylabus

 

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just an extra note

although this thread is full of my own comments.. i must add..
for Q16: is it even in the syllabus? i dont recall having done any experiment of that sort. AND it reminds me of circular motion....

 

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yay

hey rama

u're such a big help! a BIG thanks

 

[Captain Gh3y]

Both of the second 2 questions are from dotpoints that were removed after 2002. (circular motion, communication with satellites) You can still do the 2nd one though.

Hmm... 2pi*r/T is just diameter/period or distance/time, but that's been taken out. (Now if you ever see a question about the orbital velocity of a satellite you have to use centripetal force = gravitational force and solve for v)

 

[rama_v]

Both of the second 2 questions are from dotpoints that were removed after 2002. (circular motion, communication with satellites) You can still do the 2nd one though.

Hmm... 2pi*r/T is just diameter/period or distance/time, but that's been taken out. (Now if you ever see a question about the orbital velocity of a satellite you have to use centripetal force = gravitational force and solve for v)

Yeah..but its good to know v = 2pir/T because thats where Kepler's Law is derived from

 

[richz]

yeah its not really taken out, its an useful eqn