Recent content by samblue

Thankyou SO much. I have an exam tomorrow and this question seems to come up un all of the past papers but I just couldn't do it. However I still can't do the question. if I put b1/b2=2 and then ssub in values and rearrange I get : m2-m1=-.7525. Where do I go from here?

[SOLVED] Apparent magnitude of binary star? Homework Statement A binary star has a total apparent magnitude of 15.00. One component star is twice as bright as the other. a) Show that the apparent magnitude of the brighter star is 15.44. b) The fainter star has an apparent magnitude of...

On a second though to I have to use the formula: B=U0*NI/L If I do why am I given the area?

Homework Statement A long, solonoidal coil with 2000 turns produces a B field pf 3mT at its center when a current of 1A flows through the coil. If the cross sectional area of the coil is: 2*10^-3 m^-2, and the field is uniform throghout the solonoid, determine the self inductance of the oil...

Homework Statement A power line runs along the Earth's equator where the magnetic flux density, B, points from south to north and has a strength of 50*10-6T. The current in the line is 500A flowing from west to east. Find the magnitude and the direction of the fore acting on eath kilometer...

Do you have any idea of what i would be expected to write in the "describe the motion" part?

thanks

Ok but if I work out this force easily enough how is this going to tell me what then time is when its speed gets to zero?

Homework Statement A proton moving to the right along the x-axis at 3.8*10^5m/s, enters a region where the electric field of intensity 5.6*10^4n/c points to the left. How far will the proton move before its speed reaches zero? Describe the subsequent motion in deatail/ Homework...

thanks

Not really sure. Is it zero? Becasue all of the charge passes through it?

Homework Statement Ok so I', having some problems with Gauss's law. I know what it is, but I still can't get the answers right. A metallic sphere of diameter 2*10-2m has been given a charge of 2 nC. State Gauss's law. Use this to determine the electrical field at the surface of the...

No sorry i dont. I know this is almost certainly something simple which will make me feel stupid when I see the answer but at the moment I don't have the figgiest. My best guess would be to assume that the reistance and the temperature are related linerly?

sorry. its the resistivity which is directly proportional to the absolute temperature.

Homework Statement Define resistance and resistivity? A 30W, 6A bulb has a filiment which is directly prortional to the absolute temperature? At 37 degrees celcius the reisitance of the fimament is 015ohms. What is the working temperature of the filament? Homework Equations None...