#### 12th Standard Physics English Medium Free Online Test Book Back One Mark Questions - Part Three

12th Standard

Reg.No. :
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Physics

Time : 00:10:00 Hrs
Total Marks : 10
10 x 1 = 10
1. The total electric fl ux for the following closed surface which is kept inside water

(a)

$\frac { 80q }{ { \varepsilon }_{ 0 } }$

(b)

$\frac { q }{ { 40\varepsilon }_{ 0 } }$

(c)

$\frac { q }{ { 80\varepsilon }_{ 0 } }$

(d)

$\frac { q }{ { 160\varepsilon }_{ 0 } }$

2. Th e following graph shows current versus voltage values of some unknown conductor. What is the resistance of this conductor?

(a)

2 ohm

(b)

4 ohm

(c)

8 ohm

(d)

1 ohm

3. A thin insulated wire forms a plane spiral of N = 100 tight turns carrying a current I = 8 m A (milli ampere). The radii of inside and outside turns are a = 50 mm and b = 100 mm respectively.
The magnetic induction at the center of the spiral is

(a)

$5\mu T$

(b)

$7\mu T$

(c)

$8\mu T$

(d)

$10\mu T$

4. Th e fl ux linked with a coil at any instant t is given by $\Phi$B =10t2−50t+ 250 . The induced emf at t = 3s is

(a)

−190 V

(b)

−10 V

(c)

10 V

(d)

190 V

5. Consider an oscillator which has a charged particle and oscillates about its mean position with a frequency of 300 MHz. Th e wavelength of electromagnetic waves produced by this oscillator is

(a)

1 m

(b)

10 m

(c)

100 m

(d)

1000 m

6. Stars twinkle due to,

(a)

reflection

(b)

total internal refl ection

(c)

refraction

(d)

polarisation

7. A photoelectric surface is illuminated successively by monochromatic light of wavelength λ and $\frac{\lambda}{2}.$ If the maximum kinetic energy of the emitted photoelectrons in the second case is 3 times that in the fi rst case, the work function at the surface of material is

(a)

$\frac{hc}{\lambda}$

(b)

$\frac{2hc}{\lambda}$

(c)

$\frac{hc}{3\lambda}$

(d)

$\frac{hc}{2\lambda}$

8. The charge of cathode rays is

(a)

Positive

(b)

negative

(c)

neutral

(d)

not defined

9. the nuclear radius of 27 al is 3.6 fermi, the approximate nuclear radius of 64Cu is

(a)

24

(b)

1.2

(c)

4.8

(d)

3.6

10. Which one of the following is the natural nanomaterial

(a)

Peacock feather

(b)

Peacock beak

(c)

Grain of sand

(d)

Skin of the Whale