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Science Class 7th

321. The angle of incidence for which the corresponding angle of refraction is 90o is called?

A) Angle

B) Critical angle

C) Refraction

D) None

 

Answer
B

322. Maximum refraction occurs at ______ angle.

A) Right

B) Critical

C) None

Answer
B

323. Critical angle for water is?

A) 49o.

B) 50o

C) 45o

D) None

 

Answer
A

324. Critical angle of glass is?

A) 90

B) 56

C) 42o

D) 60

Answer
C

325. When the angle of incidence becomes becomes greater than the critical angle, then no refraction occurs and light reflects back, the phenomenon is called?

A) External reflection

B) Total internal reflection

C) Critical reflection

Answer
B

326. The conditions for Total internal reflection are:

A) Light must enter from a denser medium to rare medium

B) Angle of incidence must be greater than critical angle

C) Both ‘a’ and ‘b’

Answer
C

327. A reflecting prism is made of transparent glass which has _____ surfaces.

A) 3 rectangular surfaces

B) 2 triangular surfaces

C) Both ‘a’ and ‘b’

D) None of these

Answer
C

328. Each triangular surface has one angle of ______ and other two angles of 45o?

A) 90o

B) 45

C) 60

D) 180

Answer
A

329. Total internal reflection occurs in?

A) Reflecting prism

B) Periscope

C) Mirage

D) All of these

Answer
D

330. Which of the following is natural optical phenomenon?

A) Mirage

B) Prism

C) Periscope

D) None

 

Answer
A

331. In hot days, we see inverted images of distant objects on roads because of total internal reflection, the phenomenon is called?

A) Mirage

B) Reflection

C) Refraction

D) None

Answer
A

332. Mirage is optical_____.

A) Reality

B) Virtuality

C) Illusion

D) None

Answer
C

333. A fish and diver is able to see objects in the side and bottom of pond due to?

A) Refraction

B) Reflection

C) Total internal reflection

D) None

Answer
C

334. The fish or diver is able to see objects outside pond due to?

A) Total internal reflection

B) Refraction

C) Reflection

D) None of these

Answer
B

335. When beam of sun light is passed through prism, it splits up in _____ colors.

A) 8

B) 6

C) 7

D) 10

Answer
C

336. The phenomena of splitting light into its component colors is called______ of light.

A) Dispersion

B) Convergence

C) Inversion

D) None

Answer
A

337. The band of seven colors obtained is called?

A) Spectrum of light

B) Group of light

C) Band of light

D) None of these

 

Answer
A

338. Seven colors of spectrum can be denoted by?

A) VIBGYOR

B) VEBYOR

C) YORBOG

D) None

Answer
A

339. Rainbow is an example of?

A) Reflection of light

B) Total internal reflection

C) Dispersion of light

Answer
C

340. Red color appears on the _______ side of rainbow.

A) Middle

B) Upper

C) Bottom

D) Not at all

Answer
B

341. Violet color appears on the _________ side of rainbow

A) Upper

B) Middle

C) Bottom

D) Lower side

Answer
D

342. Colors that can be used to make any other color is called ______ color.

A) White

B) Primary

C) Secondary

D) None

Answer
B

343. The Primary colors are?

A) Red

B) Blue

C) Green

D) All of the above

Answer
D

344. Colors produced by mixing any two primary colors are called ______ colors.

A) Secondary

B) Primary

C) Tertiary

D) None

Answer
A

345. Peacock blue is ______ color.

A) Primary

B) Secondary

Answer
B

346. Peacock blue is which color?

A) Sky blue

B) Blue

C) Peacock color

D) Cyan

Answer
D

347. Which of the following are secondary colors?

A) Magenta

B) Yellow

C) Both ‘a’ and ‘b’

D) None

Answer
C

348. With the help of ______ Newton demonstrated that white light is combination of 7 different colors.

A) Prism

B) Newton color disc

C) Periscope

D) None

Answer
B

349. The color of an object is the color which it?

A) Reflects

B) Absorb

C) Refract

D) None

Answer
A

350. Peacock blue is which color?

A) Sky blue

B) Blue

C) Peacock color

D) Cyan

Answer
D
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