Heh, it's really just a question of how used to it you are. Like, i'm sure you have no difficulty writing numbers, and those have plenty of sharp angles. I grew up writing in both English and Chinese, so writing in kanji feels natural to me. Writing in English honestly doesn't take any less time than Chinese or Japanese.
Not gonna lie though, learning Chinese/Japanese characters takes longer than learning how to spell in English. Growing up, a significant portion of my Chinese homework from kindergarten all the way through high school literally just involved copying out a bunch of new characters about 20 times each to make it muscle memory.
As someone who grew up with Chinese, very much so at first. It does get easier though. Many characters are formed with components that also appear in many other characters. For instance, 日 shows up in 昨, 照, 朝, 明. In addition to giving you a hint as to what those characters mean (just like how all of the character listed above have something to do with the sun/day), as you go you just kind of... get used to the various components and you start thinking of them as things consisting of combinations of standard sets of lines instead of individual lines on their own. If that makes sense.
On that note, fun fact: 言 on its own means word, or speech, in Chinese. 舌 is the word for tongue. Put them together and you get 話 (speech/talk/language). Both components contain 口, which means mouth.
Meanwhile, 雨 is rain. 申, extend. 電--> lightning/electricity (picture the lightning spreading out in the rain)
電話 --> electric talk-->telephone
Haha I'm Chinese; trust me when I say that I know exactly how difficult the initial learning and retaining of kanji can be, given that Chinese is written only in hanzi. My comment about numbers was just to respond to the idea above that sharp angles and lines make a character any more time-consuming or difficult to write. It doesn't, really. Once you're used to it, it's just as fast to write in as English is. It's the initial memorisation that's the problem.
It takes almost no time to type it out on the computer though, with the proper input method. I use one where I type the romanized characters then push space to cycle through the options or choose from a list; because it displays the most commonly-used words first (and adjusts dynamically based on YOUR usage) the first choice is the one I want an overwhelming majority of the time.
...because cursive is an almost useless skill. Why waste so much time teaching kids something that most will forget, when maybe 1% will find a use for it in their life? Few people write enough for cursive to really save them any time. If you're concerned with speed or permanence or basically anything functional, type it. If you want something personal or to really remember it (if that even helps for you), then write it, but you don't need cursive to do that. I think the only person I know personally who writes in cursive is my mom, and it's chicken scratch.
That said, I doubt they're teaching anything more useful in place of it, but it's a nice thought...
It turns out that cursive writing activated the right ("artistic") side of the brain. People (kids) who are non-sequential thinkers learn reading/writing BETTER and more easily with cursive than with printing. I knew i preferred cursive, but not why until reading this - i have seen some of my own children struggle with printing, but have an easier time with cursive.
So it's not useless, even if it's less necessary than it once was.
Yes, でんわ (電話) is a general term for telephone as others have mentioned. However, if I'm not mistaken, what we call a cell phone or mobile phone English is usually referred to in Japanese as けいたい, which is short for けいたいでんわ (携帯電話) and literally means something like "carrying telephone."
The kanji is acceptable on English to Japanese translation questions.
Listening questions however are automatically generated by Duo. The contributors are unable to add multiple answer options to them so they will only accept one single 'best' answer. Since this question is derived from the hiragana course the 'best answer' must be in hiragana.
"wa" is わ, "ne" is ね,
The "wa" in こんにちは uses the hiragana for "ha" は because it is acting as a grammatical particle marking the topic of a sentence. (In Kanji it would be 「今日は」literally meaning "on the topic of this day"
The kanji for でんわ is 電話 where the "wa" is the part of the word meaning "speech/talk" (lit. 'electric talk')
This same kanji is found in the verb 話す ・はなす・hanasu・"to speak"
There's a long historical explanation about the shift in kana pronunciations but just know that as a topic particle は is "wa" (this is the pronunciation you'll usually see when this kana is by itself), and as part of a word it is its standard pronunciation "ha" (most often seen in pronunciation guides like these hiragana lessons and in set expressions written in kana only since full words are usually written in their kanji form)