brodidit for students
ہوم / مشق / ایم ڈی کیٹ / طبیعیات / جدید طبیعیات
جدید طبیعیات
6 سوالات: ایم ڈی کیٹ طبیعیات، جوابات اور وضاحت کے ساتھ۔
جوابی کنجی کے ساتھ قابلِ پرنٹ ورک شیٹ
-
The photoelectric effect supports the idea that light behaves as:
- 1 A purely continuous wave
- 2 A particle (photons)
- 3 A sound wave
- 4 A longitudinal wave
جواب دیکھیں
درست جواب: A particle (photons)
Light arrives in packets of energy, called photons. A photon of high enough energy can free an electron at once.
-
The energy of a photon is given by:
- 1 E = hf
- 2 E = qV / t
- 3 E = mc
- 4 E = 1/2 mv²
جواب دیکھیں
درست جواب: E = hf
E = hf, where h is Planck's constant and f is the frequency of the light.
-
What fraction of a radioactive sample remains after 3 half-lives?
- 1 1/8
- 2 1/6
- 3 1/9
- 4 1/3
جواب دیکھیں
درست جواب: 1/8
Each half-life halves the amount: 1/2 x 1/2 x 1/2 = 1/8.
-
In beta-minus decay, a neutron changes into:
- 1 Two protons
- 2 A proton and a positron
- 3 A proton, an electron and an antineutrino
- 4 A helium nucleus
جواب دیکھیں
درست جواب: A proton, an electron and an antineutrino
A neutron becomes a proton and the nucleus emits an electron (the beta particle) and an antineutrino.
-
Which type of radiation is the most penetrating?
- 1 Gamma rays
- 2 All penetrate equally
- 3 Alpha particles
- 4 Beta particles
جواب دیکھیں
درست جواب: Gamma rays
Gamma rays pass through the body and need thick lead or concrete to be stopped. Alpha particles are stopped by paper.
-
The mass number of an atom is equal to the number of:
- 1 Protons plus neutrons
- 2 Neutrons only
- 3 Electrons plus protons
- 4 Protons only
جواب دیکھیں
درست جواب: Protons plus neutrons
The mass number counts all nucleons, which are the protons and the neutrons.