{"questions":[{"id":"matric-phy10-sound-01","v":1,"subject":"physics-10","chapter":"sound","seed":true,"difficulty":1,"stem":"Sound travels fastest in:","options":["Steel","Water","Air","A vacuum"],"answer":0,"explain":{"en":"Sound is fastest in solids, slower in liquids and slowest in gases: roughly 5,000 m/s in steel, 1,500 m/s in water and 340 m/s in air. It cannot travel through a vacuum at all.","ur":"آواز ٹھوس میں سب سے تیز، مائع میں کم اور گیس میں سب سے آہستہ چلتی ہے: اسٹیل میں تقریباً 5,000، پانی میں 1,500 اور ہوا میں 340 m/s۔ خلا میں آواز نہیں چلتی۔"},"source":{"kind":"parcha-original"},"status":"sample","exam":"matric"},{"id":"matric-phy10-sound-02","v":1,"subject":"physics-10","chapter":"sound","difficulty":1,"stem":"The audible frequency range for a normal human ear is about:","options":["2 Hz to 2,000 Hz","200 Hz to 200,000 Hz","20 Hz to 20,000 Hz","0 Hz to 2 Hz"],"answer":2,"explain":{"en":"People with normal hearing hear about 20 Hz to 20,000 Hz (20 kHz). Below 20 Hz is infrasound; above 20 kHz is ultrasound.","ur":"عام انسان تقریباً 20 Hz سے 20,000 Hz تک سنتا ہے۔ 20 Hz سے کم انفراساؤنڈ اور 20 kHz سے زیادہ الٹراساؤنڈ کہلاتی ہے۔"},"source":{"kind":"parcha-original"},"status":"sample","exam":"matric"},{"id":"matric-phy10-sound-03","v":1,"subject":"physics-10","chapter":"sound","difficulty":1,"stem":"Ultrasound has frequencies:","options":["Below 20 Hz","Between 20 Hz and 2,000 Hz","Exactly 20 kHz","Above 20 kHz"],"answer":3,"explain":{"en":"Ultrasound is sound above the upper limit of human hearing, 20 kHz. It is used in medical scans, cleaning and sonar.","ur":"الٹراساؤنڈ وہ آواز ہے جو انسانی سماعت کی بالائی حد 20 kHz سے اوپر ہو۔ یہ طبی اسکین، صفائی اور سونار میں استعمال ہوتی ہے۔"},"source":{"kind":"parcha-original"},"status":"sample","exam":"matric"},{"id":"matric-phy10-sound-04","v":1,"subject":"physics-10","chapter":"sound","difficulty":2,"stem":"The loudness of a sound depends mainly on its:","options":["Frequency","Amplitude","Wavelength alone","Speed"],"answer":1,"explain":{"en":"A larger amplitude carries more energy, so the sound is louder. Frequency decides the pitch, not the loudness.","ur":"زیادہ ایمپلیٹیوڈ زیادہ توانائی لے جاتا ہے، اس لیے آواز اونچی ہوتی ہے۔ فریکوئنسی پچ طے کرتی ہے، بلندی نہیں۔"},"source":{"kind":"parcha-original"},"status":"sample","exam":"matric"},{"id":"matric-phy10-sound-05","v":1,"subject":"physics-10","chapter":"sound","difficulty":1,"stem":"The pitch of a sound depends on its:","options":["Frequency","Amplitude","Loudness","Quality"],"answer":0,"explain":{"en":"Higher frequency means higher pitch: a whistle sounds shrill because of its high frequency. Amplitude affects loudness, and the mix of overtones gives quality (timbre).","ur":"زیادہ فریکوئنسی کا مطلب اونچی پچ ہے: سیٹی کی آواز تیز اسی لیے لگتی ہے۔ ایمپلیٹیوڈ بلندی اور اوور ٹونز آواز کی کوالٹی طے کرتے ہیں۔"},"source":{"kind":"parcha-original"},"status":"sample","exam":"matric"},{"id":"matric-phy10-sound-06","v":1,"subject":"physics-10","chapter":"sound","difficulty":3,"stem":"To hear a distinct echo in air (speed of sound 340 m/s), the reflecting surface must be at least about how far away?","options":["34 m","10 m","17 m","170 m"],"answer":2,"explain":{"en":"The ear keeps a sound for about 0.1 s, so the echo must return after at least 0.1 s. In 0.1 s sound travels 340 × 0.1 = 34 m there and back, so the surface must be at least 17 m away.","ur":"کان آواز کو تقریباً 0.1 s تک محسوس کرتا ہے، اس لیے بازگشت کم از کم 0.1 s بعد آنی چاہیے۔ اس وقت میں آواز آنا جانا 34 m طے کرتی ہے، یعنی دیوار کم از کم 17 m دور ہو۔"},"source":{"kind":"parcha-original"},"status":"sample","exam":"matric"}]}