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  1. hellodjfos;s'ff

    Physics: Post your doubts here!

    Can't be C, because if the resistance was infinite, the ammeter would show an error sign. If the pd is zero between the two points, then the ammeter would show zero since no current would flow between those point.
  2. hellodjfos;s'ff

    Physics: Post your doubts here!

    Your welcome.
  3. hellodjfos;s'ff

    Physics: Post your doubts here!

    Oh yeah i forgot to answer your main question lol. They are asking us to find the order(standard form) of frequency of the visible spectrum.
  4. hellodjfos;s'ff

    Physics: Post your doubts here!

    You apply v=f(lamda) to find the frequency. You know the wavelength of the visible spectrum ranges from 400nm to 700nm, and that the velocity of electromagnetic waves is 3x10^8. So 3x10^8=400x10^-9(f) The f turns out to be 7.5x10^14 Hz. Hence, the order of frequency is 10^14 Hz(C).
  5. hellodjfos;s'ff

    Physics: Post your doubts here!

    I answered this on page 898. You check the answer there.
  6. hellodjfos;s'ff

    AS Physics P1 MCQs Preparation Thread.

    Take O as your pivot. Since the structure is in equilibrium, the anticlockwise moments=clockwise moments. 3(2)+4(0)+4(2sin30)=F(5) -----> 6+4=5F -----> F=2N(B) The 4N force has not moment because there is no perpendicular distance from it's line of force to the pivot.
  7. hellodjfos;s'ff

    Physics: Post your doubts here!

    It's not really a ratio. You got to understand how stationary waves move and work. Check this gif here to understand: http://www.sengpielaudio.com/StandingWaves.htm . There are 5 stages to a cycle/period of a stationary wave. First is the point/state in which it starts usually when it is up...
  8. hellodjfos;s'ff

    Physics: Post your doubts here!

    When finding the gravitational energy of regular objects, you take their height from the centre of mass. Initially, the centre of mass of the block is 0.3m above the edge of the step. So the initial gravitational energy is 500(0.8+0.3)=550J. After the block falls, its centre of mass is 0.2m...
  9. hellodjfos;s'ff

    Physics: Post your doubts here!

    15: It is A simply because the ball's energy is being converted from kinetic to gravitational, since there is no air resistance, none of the ball's energy is being lost to the air as heat. So, the ball's energy is conserved. B is incorrect because the option says that the momentum of the ball is...
  10. hellodjfos;s'ff

    Physics: Post your doubts here!

    For 9, since the force of gravity acting on her is constant, her acceleration and deceleration would be constant too. Consequently, the gradient of the graphs must be constant too, this rules out B and C. To decide between A and D, find the diagram with a completely vertical line which would be...
  11. hellodjfos;s'ff

    Physics: Post your doubts here!

    Also, search for images of actual experiment results for double slit and diffraction grating to understand this. Both are horizontal. The diffraction grating spreads the light into the colour spectrum, horizontally. While, double slit produced dark and bright fringes horizontally as well.
  12. hellodjfos;s'ff

    Physics: Post your doubts here!

    Yes, there would be diffraction in this question. Yes, if you had a double slit, you would also have a horizontal pattern. In diagrams, the pattern appears to be vertical but in reality it's horizontal. If you do a practical for this you would know(CIE encourages this).
  13. hellodjfos;s'ff

    Physics: Post your doubts here!

    Your welcome
  14. hellodjfos;s'ff

    Physics: Post your doubts here!

    If you work the other way around, I think you should get the same equation, regardless of that, it wouldn't matter whether it's r2-r1 or r1-r2.
  15. hellodjfos;s'ff

    Physics: Post your doubts here!

    For 37, again you apply kirchhoff's 2nd law. Two cells are supporting each other while one is opposing. 2E-E=I(R+R+R) ---> E=I(3R) ----> R=E/3I . Now, you can find the pd used up by resistor in the left part of the circuit using V=IR. V=I * E/3I ----> V=E/3 . So that means that a remaining 2E/3...
  16. hellodjfos;s'ff

    Physics: Post your doubts here!

    Not necessarily, if waves need to be coherent, they must have a constant phase difference. Usually when waves are produced to be coherent they use the same source to produce the waves so yes, mostly they have the same frequency but it's not required.
  17. hellodjfos;s'ff

    Physics: Post your doubts here!

    No probs bro
  18. hellodjfos;s'ff

    Physics: Post your doubts here!

    For 36, you have to apply kirchhoff's 2nd law. There are two points where the voltmeter is connected, I will name the point on the right, A and the one on the left, B. So at A, the pd is E because it just came out of the cell and hasn't been used up(I am treating the internal resistances as...
  19. hellodjfos;s'ff

    Physics: Post your doubts here!

    Precision is the number of decimal places to which a measurement is taken, while accuracy is the closeness of the measurements to the actual values. So 2.33 is more accurate(closer to 2.321, you can find this out by subtracting the measurement and the actual value), while 2.344 is more precise...
  20. hellodjfos;s'ff

    Physics: Post your doubts here!

    Yeah sure. It would be good for my revision too.
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