Bihar Board Physics Exam Answer Key 2019 Set-B

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  1. The resistance of an ideal ammeter is- Zero
  2. Light owes its color to its- Frequency
  3. The Boolean expression for NAND gate is- Y = A.B
  4. The wavefront due to the point source at a finite distance from the source is- Spherical
  5. The height of a TV tower at a certain places to 245m the maximum distance up to which its program can be received is- 56Km
  6. In an alternating current circuit the phase difference between current and voltage is V then the wattless component of current will be –1 SINϕ Option C
  7. Equivalent focal length of two lens in contact having power- 15 D and + 5D will be – (-)10
  8. Deviation of a thin prism of refractive index n and angle of prism A is- -(n-1)A
  9. A Convex lens made from such material which refractive index is 1.5. This lens is immersed in water (u=1.33), then behaves like as- Converging Lens
  10. Unit of surface charge density is – Cm2
  11. With the increase of temperature resistivity of semiconductor –Decreases
  12. The Solar spectrum is- Continuous
  13. The magnifying power of an astronomical telescope for normal adjustment is – Option A
  14. When two bulbs of power 60w and 40w are connected in series then power of the combination will be – 24W
  15. Electric potential in an equatorial position of an electric dipole is- Zero
  16. If Q is equal to charge is placed inside in a spherical surface then total flux coming out from the whole surface will be- qE0
  17. The torque experienced by a current loop of magnetic moment M placed in a magnetic field is – M*B Option A
  18. At constant potential difference resistance of an electric circuit is half the value of heat produced will be Double / Two times
  19. The energy of a photon of wavelength λ is – hc/λ
  20. The time in which radioactive substance become half of its initial amount is called – Half-Life
  21. The Stored energy of capacitor changed to 100 volt is 1-joule capacitance of the capacitor is-2×10-4 F
  22. Cylindrical lenses are used to correct eye defect called- Astigmatism
  23. In Earth’s magnetic field Bh a frequency of oscillation of magnetic needle is in then –N2 α Bh (B)
  24. Two point charges of class 10 and minus 10 are placed at a distance 40 cm and potential energy of a system will be -25J
  25. The susceptibility of a paramagnetic substance is – Constant
  26. The direction of propagation of the electromagnetic wave is – Option D
  27. The value of an angle of dip at Earth’s magnetic pole is- 90 Degree
  28. The current flowing in the wire is one ampere is a charge of an electron is 1.6×10^19 coulombs the number of electrons flowing through wire per second is – 6.25*10^18
  29. Which one of the following has a maximum refractive index – Diamond
  30. The ratio of root mean square value and peak value of alternating current is – 1√2(Option B)
  31. The modulation index in an Amplitude Modulation- Lies between zero and 1
  32. Working of the dynamo is based on the principle of-Electromagnetic Induction
  33. Power of an electric circuit is – V2/R
  34. The power of an l-r circuit is – B
  35. In a step up Transformer number of turns in primary and secondary cells and N1 and N2 then- N2>N1