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

 

322. Maximum refraction occurs at ______ angle.

A) Right

B) Critical

C) None

323. Critical angle for water is?

A) 49o.

B) 50o

C) 45o

D) None

 

324. Critical angle of glass is?

A) 90

B) 56

C) 42o

D) 60

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

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

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

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

A) 90o

B) 45

C) 60

D) 180

329. Total internal reflection occurs in?

A) Reflecting prism

B) Periscope

C) Mirage

D) All of these

330. Which of the following is natural optical phenomenon?

A) Mirage

B) Prism

C) Periscope

D) None

 

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

332. Mirage is optical_____.

A) Reality

B) Virtuality

C) Illusion

D) None

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

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

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

A) 8

B) 6

C) 7

D) 10

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

A) Dispersion

B) Convergence

C) Inversion

D) None

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

 

338. Seven colors of spectrum can be denoted by?

A) VIBGYOR

B) VEBYOR

C) YORBOG

D) None

339. Rainbow is an example of?

A) Reflection of light

B) Total internal reflection

C) Dispersion of light

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

A) Middle

B) Upper

C) Bottom

D) Not at all

341. Violet color appears on the _________ side of rainbow

A) Upper

B) Middle

C) Bottom

D) Lower side

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

A) White

B) Primary

C) Secondary

D) None

343. The Primary colors are?

A) Red

B) Blue

C) Green

D) All of the above

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

A) Secondary

B) Primary

C) Tertiary

D) None

345. Peacock blue is ______ color.

A) Primary

B) Secondary

346. Peacock blue is which color?

A) Sky blue

B) Blue

C) Peacock color

D) Cyan

347. Which of the following are secondary colors?

A) Magenta

B) Yellow

C) Both ‘a’ and ‘b’

D) None

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

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

A) Reflects

B) Absorb

C) Refract

D) None

350. Peacock blue is which color?

A) Sky blue

B) Blue

C) Peacock color

D) Cyan